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một bài bđt khó nha cho a,b,c là các số dương thỏa mãn a+b+c=3. Tìm giá trị nhỏ nhất của biểu thức sau:
P=1/1+a^2 +1/1+b^2 +1/1+c^2
tiếng anh
PART TWO: PHONES
I. Circle the letter A, B, C or D before the word in each group that has the underlined part pronounced differently from the rest. (0,2 x 10 = 2 pts)
1. A. promised B. hoped C. booked D. burned
2. A. though B. ought C. thought D. bought
3. A. hard B. carry C. card D. yard
4. A. try B. why C. heavy D. dry
5. A. cool B. food C. look D. Flood
II. Choose the word whose main stress is placed differently from the others in each group.(0,2 x 10= 2 pts)
1. A. realize B. improve C. possible D. comfortable
2. A. important B. especially C. prefer D. influence
3. A. general B. opinion C. abroad D. surprise
4. A. comfort B. nation C. apply D. moment
5. A. medical B. advise C. vegetables D. physical
PART THREE: VOCABULARY AND GRAMMAR (0.2 x 30 = 6.0 pts)
I. Circle the best option A, B, C or D to complete the following sentences. (0,2 x 10 = 2 pts)
1. The teacher told him ___________ up late.
A. to not stay B. to stay not C. to stay not D. not to stay
2. My father is good at ____________ English.
A. speaking B. spoken C. speak D. to speak
3. We are all ________ that you passed your English exam. Congratulation!
A. relieved B. afraid C. delighted D. certain
4. “__________to come and have dinner with us?” “I’d love to but I’m very busy”.
A. would you mind B. Could you please
C. Would you D. Do you enjoy
5. I am very _____________ in the information you have given me.
A. concerned B. interested C. surprised D. worried
6. Can you tell me where ______________ ?
A. she does B. does she C. she is D. is she
7. You have to work ____________ for the coming exam.
A. hardly B. more hardly C. more hard D. hard
8. I saw her _____________ the flowers in the garden.
A. watering B. watered C. be watered D. is watering
9. They had their luggage ___________ by the porter.
A. carry B. carrying C. to carry D. carried
10. She often spends her weekend ___________ through pleasant open countryside.
A. travel B. traveling C. to travel D. to traveling
II. Use the words given in brackets to form a word that fits in the space. (0,2 x 10 = 2pts)
1. This book has a lot of information. It's very _________________. (use)
2. You'll meet the tour guide on your ________________ at the hotel. (arrive)
3. Our post is delivered ______________________except for Saturday (day)
4. Ha Long Bay was by UNESCO as a World Heritage Site. (recognition)
5. Relax for some minutes and you'll feel more ______________ . (comfort)
6. His parents are very __________________ of him. (pride)
7. "The lost shoes" is one of the _______________ stories I best. (tradition)
8. The _____________ from Hanoi to London was delayed in two hours. (fly)
9. I'm sure that I have connected the printer ___________ . (proper)
10. Each of my friends has a _________________ character. (differ)
Hòa tan hoàn toàn m gam một oxit sắt bằng hung dịch H2So4 đặc nóng thu a mol So2 duy nhất ,Mặt khác , sau khi khử hoàn toàn m gam oxit trên bằng CO ở nhiệt độ cao rồi cho toàn bộ lượng fe tạo thành vào h2so4 đặc nóng dư thu 9 a mol so2 duy nhất ,Tìm công thức oxit sắt