Three signal lights were set to flash every certain specified time . The first light flashes every 12 second , the second flashes every 30 seconds and the third one every 66 seconds . The signal ligh...

NT

nguyễn thành nam

5 tháng 4 2019 - olm

Three signal lights were set to flash every certain specified time . The first light flashes every 12 second , the second flashes every 30 seconds and the third one every 66 seconds . The signal lights flash simultaneously at 8:30 a.m . At what time will the signal lights next flash together

#Toán lớp 8

2

CD

Chu Diệu Linh

5 tháng 4 2019

Đề bài

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NH

Nguyen Hoang Ky Anh

29 tháng 4 2019

12=3.2^2

30=3.2.5

66=11.2.3

BCNN(12,30,66)=3.2^2.11.5=660(sec)

660sec=11min

8:30min+11min=8:41min

=>The signal lights will flash together at 8:41

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TC

TXT Channel Funfun

26 tháng 10 2017 - olm

Tom and Jelly embarked on a moving escalator to the second floor of a shopping mall. Tom walked up the escalator at a speed of 2 steps every second. At the same time, Jelly walked up the same escalator at a speed of 3 steps every 2 seconds. Tom arrived at the second floor in 25 seconds. It took Jelly 30 seconds to reach same floors. How many steps had the escalator when it stationary ?

#Toán lớp 6

0

TM

Trần Minh Ánh

11 tháng 4 2017

Traffic lights only became necessary in the 19th century, when traffic began to increase. A traffic signal (1)..................................... by J O Knight, a railway signaling engineer, was installed outside the Houses of Parliament in London in 1868. It looked like a railway signal of the time but a few weeks later it blew up,and signal of this type were no (2)....................................... used. The mordern traffic light is an American invention, the first red and green...

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#Tiếng anh lớp 7

3

NH

N H T

4 tháng 8 2017

1.invented
2.longer
3.until
4.use
5.different

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TN

Tuệ nguyễn đẹp gái

23 tháng 8 2019

ngu! bài dễ mà ko biết

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LQ

Lê Quỳnh Anh

26 tháng 2 2018

A thunder usually follows lightning by five seconds for every mile between the flash and the observer A. A thunder B. seconds C. every mile...

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#Mẫu giáo

1

DH

Dương Hoàn Anh

26 tháng 2 2018

Đáp án là A. A thunder => thunder, vì Thunder : sấm, là danh từ không đếm được, nên không dùng mạo từ “a”

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LH

Lê Hoàng Nhật Anh

VIP

19 tháng 9 2021 - olm

Question 3. Two neon lights are turned on at the same time. One blinks every 4 seconds and the other blinks every 6 seconds. Answer the following questions, give your answer only.a) How long will it take them to blink simultaneously for the first time after they are turned on? (simultaneously: at the same time)b) How many times will they blink simultaneously in the first 70 seconds after they are turned...

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#Toán lớp 5

4

UP

☪ú⚛Đêm ( PhóღteamღVTP )

19 tháng 9 2021

Question 3. Two neon lights are turned on at the same time. One blinks every 4 seconds and the other blinks every 6 seconds. Answer the following questions, give your answer only.

a) How long will it take them to blink simultaneously for the first time after they are turned on? (simultaneously: at the same time)

a = 6 s

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UP

☪ú⚛Đêm ( PhóღteamღVTP )

19 tháng 9 2021

Question 3. Two neon lights are turned on at the same time. One blinks every 4 seconds and the other blinks every 6 seconds. Answer the following questions, give your answer only.

b) How many times will they blink simultaneously in the first 70 seconds after they are turned on?

b) 11

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KL

khanh le

1 tháng 11 2021

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#Tiếng anh lớp 7

1

NH

Nguyễn Hải Yến Nhi

1 tháng 11 2021

1....2 hours doing his homework everyday

2......was raining heavily, we were late for school

3......had a brother

4.....has 32 students

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NM

Ngọc My

7 tháng 3 2022

* Combine two sentences into one. Use the sentence in brackets to make a non-defining relative clause.1. The National Library opens every weekday. (The library is on the second floor).The National Library, which is on the second floor, opens every weekday.2. Developed countries are helping developing countries. (They are ahead in education and wealth.)Developed countries, which are ahead in education and wealth, are helping developing countries.3. Internationalisation has brought about both...

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#Tiếng anh lớp 9

0

DM

Dương Minh

3 tháng 9 2019

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. Lighthouses are towers with strong lights that help mariners plot their position, inform them that land is near, and warn them of dangerous rocks and reefs. They are placed at prominent points on the coast and on islands, reefs, and sandbars. Every lighthouse has a distinctive pattern of light known as its characteristic. There are five basic...

Đọc tiếp

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Lighthouses are towers with strong lights that help mariners plot their position, inform them that land is near, and warn them of dangerous rocks and reefs. They are placed at prominent points on the coast and on islands, reefs, and sandbars.

Every lighthouse has a distinctive pattern of light known as its characteristic. There are five basic characteristics: fixed, flashing, occulting, group flashing, and group occulting. A fixed signal is a steady beam. A flashing signal has periods of darkness longer than periods of light, while an occulting signal’s periods of light are longer. A group-flashing light gives off two or more flashes at regular intervals, and a group - occulting signal consists of a fixed light with two or more periods of darkness at regular intervals. Some lighthouses use lights of different colors as well, and today, most lighthouses are also equipped with radio beacons. The three types of apparatus used to produce the signals are the catoptric, in which metal is used to reflect the light; the dioptric, in which glass is used; and the catadioptric, in which both glass and metal are used.

In the daytime, lighthouses can usually be identified by their structure alone. The most typical structure is a tower tapering at the top, but some, such as the Bastion Lighthouse on the Saint Lawrence River, are shaped like pyramids, and others, such as the Race Rock light, look like wooden houses sitting on high platforms. Still others, such as The American Shoal lighthouse off the Florida Coast, are skeletal towers of steel. Where lighthouses might be contused in daylight, they can be distinguished by day- marker patterns - designed of checks and stripes painted in vivid colors on lighthouse walls.

In the past, the job of lighthouse keeper was lonely and difficult if somewhat romantic. Lighthouse keepers put in hours of tedious work maintaining the lights. Today, lighthouses are almost entirely automated with humans supplying only occasional maintenance. Because of improvements in navigational technology, the importance of lighthouses has diminished. There are only about 340 functioning lighthouses in existence in the United States today, compared to about 1,500 in 1900, and there are only about 1,400 functioning lighthouses outside the United States. Some decommissioned lighthouses have been preserved as historical monument.

According to the passage, what kind of signal has long periods of light that are regularly broken by two or more periods of darkness?

A. Flashing

B. Group occulting

C. occulting

D. Group flashing

#Mẫu giáo

1

NH

Nguyen Hoang Hai

3 tháng 9 2019

Đáp án B.

Key words: kind of signal, long periods of light broken by two or more periods of darkness

Clue: a group-occulting signal consist of a fixed light with two or more periods of darkness at regular intervals: tín hiệu ánh sáng lấp ló theo nhóm bao gồm một ánh sáng cố định với hai hoặc nhiều chu kỳ tối diễn ra trong những khoảng cách đều đặn

Vậy đáp án chính xác là B. Group occulting

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LQ

Lê Quỳnh Anh

23 tháng 8 2017

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. Lighthouses are towers with strong lights that help mariners plot their position, inform them that land is near, and warn them of dangerous rocks and reefs. They are placed at prominent points on the coast and on islands, reefs, and sandbars. Every lighthouse has a distinctive pattern of light known as its characteristic. There are five basic...

Đọc tiếp

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Lighthouses are towers with strong lights that help mariners plot their position, inform them that land is near, and warn them of dangerous rocks and reefs. They are placed at prominent points on the coast and on islands, reefs, and sandbars.

Every lighthouse has a distinctive pattern of light known as its characteristic. There are five basic characteristics: fixed, flashing, occulting, group flashing, and group occulting. A fixed signal is a steady beam. A flashing signal has periods of darkness longer than periods of light, while an occulting signal’s periods of light are longer. A group-flashing light gives off two or more flashes at regular intervals, and a group - occulting signal consists of a fixed light with two or more periods of darkness at regular intervals. Some lighthouses use lights of different colors as well, and today, most lighthouses are also equipped with radio beacons. The three types of apparatus used to produce the signals are the catoptric, in which metal is used to reflect the light; the dioptric, in which glass is used; and the catadioptric, in which both glass and metal are used.

In the daytime, lighthouses can usually be identified by their structure alone. The most typical structure is a tower tapering at the top, but some, such as the Bastion Lighthouse on the Saint Lawrence River, are shaped like pyramids, and others, such as the Race Rock light, look like wooden houses sitting on high platforms. Still others, such as The American Shoal lighthouse off the Florida Coast, are skeletal towers of steel. Where lighthouses might be contused in daylight, they can be distinguished by day- marker patterns - designed of checks and stripes painted in vivid colors on lighthouse walls.

In the past, the job of lighthouse keeper was lonely and difficult if somewhat romantic. Lighthouse keepers put in hours of tedious work maintaining the lights. Today, lighthouses are almost entirely automated with humans supplying only occasional maintenance. Because of improvements in navigational technology, the importance of lighthouses has diminished. There are only about 340 functioning lighthouses in existence in the United States today, compared to about 1,500 in 1900, and there are only about 1,400 functioning lighthouses outside the United States. Some decommissioned lighthouses have been preserved as historical monument.

According to the passage, what kind of signal has long periods of light that are regularly broken by two or more periods of darkness?

A. Flashing

B. Group occulting

C. occulting

D. Group flashing

#Mẫu giáo

1

DH

Dương Hoàn Anh

23 tháng 8 2017

Đáp án B.

Key words: kind of signal, long periods of light broken by two or more periods of darkness

Clue: a group-occulting signal consist of a fixed light with two or more periods of darkness at regular intervals: tín hiệu ánh sáng lấp ló theo nhóm bao gồm một ánh sáng cố định với hai hoặc nhiều chu kỳ tối diễn ra trong những khoảng cách đều đặn

Vậy đáp án chính xác là B. Group occulting

Đúng(0)

LQ

Lê Quỳnh Anh

21 tháng 1 2017

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. Lighthouses are towers with strong lights that help mariners plot their position, inform them that land is near, and warn them of dangerous rocks and reefs. They are placed at prominent points on the coast and on islands, reefs, and sandbars. Every lighthouse has a distinctive pattern of light known as its characteristic. There are five basic...

Đọc tiếp

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Lighthouses are towers with strong lights that help mariners plot their position, inform them that land is near, and warn them of dangerous rocks and reefs. They are placed at prominent points on the coast and on islands, reefs, and sandbars.

Every lighthouse has a distinctive pattern of light known as its characteristic. There are five basic characteristics: fixed, flashing, occulting, group flashing, and group occulting. A fixed signal is a steady beam. A flashing signal has periods of darkness longer than periods of light, while an occulting signal’s periods of light are longer. A group-flashing light gives off two or more flashes at regular intervals, and a group - occulting signal consists of a fixed light with two or more periods of darkness at regular intervals. Some lighthouses use lights of different colors as well, and today, most lighthouses are also equipped with radio beacons. The three types of apparatus used to produce the signals are the catoptric, in which metal is used to reflect the light; the dioptric, in which glass is used; and the catadioptric, in which both glass and metal are used.

In the daytime, lighthouses can usually be identified by their structure alone. The most typical structure is a tower tapering at the top, but some, such as the Bastion Lighthouse on the Saint Lawrence River, are shaped like pyramids, and others, such as the Race Rock light, look like wooden houses sitting on high platforms. Still others, such as The American Shoal lighthouse off the Florida Coast, are skeletal towers of steel. Where lighthouses might be contused in daylight, they can be distinguished by day- marker patterns - designed of checks and stripes painted in vivid colors on lighthouse walls.

In the past, the job of lighthouse keeper was lonely and difficult if somewhat romantic. Lighthouse keepers put in hours of tedious work maintaining the lights. Today, lighthouses are almost entirely automated with humans supplying only occasional maintenance. Because of improvements in navigational technology, the importance of lighthouses has diminished. There are only about 340 functioning lighthouses in existence in the United States today, compared to about 1,500 in 1900, and there are only about 1,400 functioning lighthouses outside the United States. Some decommissioned lighthouses have been preserved as historical monument.

For which of the following does the author NOT provide a scientific example in the third paragraph?

A. A lighthouse shaped like a pyramid.

B. A lighthouse made of steel.

C. A lighthouse with day-marker patterns.

D. A lighthouse that resembles a house on a platform.

#Mẫu giáo

1

DH

Dương Hoàn Anh

21 tháng 1 2017

Đáp án C.

Key words: not, scientific example, third paragraph

Clue: The most typical structure is a tower tapering at the top, but some, such as the Bastion Lighthouse on the Saint Lawrence River, are shaped like pyramids, and others, such as the Race Rock light, look like wooden houses sitting on high platforms. Still others, such as The American Shoal lighthouse off the Florida Coast, are skeletal of steel: Cấu trúc điển hình nhất là tháp nhọn trên đỉnh, nhưng một vài ngọn hải đăng như ngọn Bastion trên sông Saint Lawrence có hình dạng như kim tự tháp, và những ngọn khác như ngọn Race Rock thì trông như ngôi nhà gỗ nằm trên nền đất cao. Ngoài ra còn có những ngọn hải đăng như ngọn America Shoal trên bờ biển Florida thì như bộ xương bằng thép.

→ Đáp án là C. A lighthouse with day-marker patterns: một ngọn hải đăng với mẫu vẽ đánh dấu ngày Các đáp án còn lại đều có ví dụ cụ thể:

A. A lighthouse shaped like a pyramid: một ngọn hải đăng có hình dạng như kim tự tháp

B. A lighthouse made of steel: một ngọn hải đăng làm từ thép

D. A lighthouse that resembles a house on a platform: một ngọn hải đăng giống như ngôi nhà trên nền đất

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