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 from 35 to 42.Life in the UniverseExobiology is the study of life that originates from outside of Earth. As yet, of course, no such life forms have been found. Exobiologists, however, have done important work in the theoretical study of where life is most likely to evolve, and what those extrateưestrial life forms might be like.What sorts of planets are most...
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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 from 35 to 42.
Life in the Universe
Exobiology is the study of life that originates from outside of Earth. As yet, of course, no such life forms have been found. Exobiologists, however, have done important work in the theoretical study of where life is most likely to evolve, and what those extrateưestrial life forms might be like.
What sorts of planets are most likely to develop life? Most scientists agree that a habitable planet must be terrestrial, or rock-based, with liquid surface water and biogeochemical cycles that somewhat resemble Earth’s. Water is an important solvent involved in many biological processes. Biogeochemical cycles are the continuous movement and transformation of materials in the environment. These cycles include the circulation of elements and nutrients upon which life and the Earth’s climate depend. Since (as far as we know) all life is carbon-based, a stable carbon cycle is especially important.
The habitable zone is the region around a star in which planets can develop life. Assuming the need for liquid surface water, it follows that most stars around the size of our sun will be able to sustain habitable zones for billions of years. Stars that are larger than the sun are much hotter and bum out more quickly; life there may not have enough time to evolve. Stars that are smaller than the sun have different problem. First of all, planets in their habitable zones will be so close to the star that they will be “tidally locked” – that is one side of the planet will always face the star in perpetual daylight with the other side in the perpetual night. Another possible obstacle to life on smaller stars is that they tend to vary in their luminosity, or brightness, due to flares and “star spots”. The variation can be large enough to have harmful effects on the ecosystem.
Of course, not all stars of the right size will give rise to life; they also must have terrestrial planets with the right kind of orbits. Most solar systems have more than one planet, which influence each other’s orbits with their own gravity. Therefore, in order to have a stable system with no planets flying out into space, the orbits must be a good distance from one another. Interestingly, the amount of space needed is roughly the width of a star’s habitable zone. This means that for life to evolve, the largest possible number of life-supporting planets in any star’s habitable zone is two.
Finally, not all planets meeting the above conditions will necessarily develop life. One major threat is large, frequent asteroid and comet impacts, which will wipe out life each time it tries to evolve. The case of Earth teaches that having large gas giants, such as Saturn and Jupiter,.in the outer part of the solar system can help keep a planet safe for life. Due to their strong gravitation, they tend to catch or deflect large objects before they can reach Earth.
It can be inferred from paragraph 3 that
A. the Earth is in the sun’s habitable zone
B. the Earth is tidally locked to the sun
C. the sun varies in its luminosity
D. variations in luminosity help life to develop
Relative clause:
1) Astronomy is one of the world oldest sciences. It is the study of planets and stars.
➞ Astronomy which is the study of planets and stars is one of the world oldest sciences
2) The vegetables are grown without chemicals. They are sold in supermarkets.
➞ the vegetables which are sold in supermarkets are grown without chemicals
3) People have marched to London. They are protesting against pollution.
➞ people who are protesting against pollution have marched to London
4) The police never found the money. It was stolen in the robbery.
➞ the police never found the money which was stolen in the robbery
5) There was a big red car. It had been parked outside the house.
➞ there was a big red car which had been parked outside the house
6) Libya is a leading producer of oil. It is a country in North Africa.
➞ Libya which is a country in North Africa is a leading producer of oil
7) A chemical company has been bankrupt. It employed 4000 people.
➞ A chemical company which employed 4000 people has been bankrupt
8) A new drug may gives us eternal youth. It was developed by a British university.
➞ A new drug may which was developed by a British university gives us eternal youth
9) A new motorway is planned. It will cost 500 million pound.
➞ A new motorway which will cost 500 million pound is planned
10) Some weapons belong to the IRA. They are found at a flat in Bristol.
➞ Some weapons who are found at a flat in Bristol belong to the IRS
11) John Quincy Adams was born on July 11, 1767. He was the sixth president of the United States.
➞ John Quincy Adams who was the sixth president of the United States was born on July11, 1767
12) There were some children. They were swimming in the river.
➞There were some children who were swimming in the river
13) Tennis fans have been queuing all night at Wimbledon. They hope to buy tickets.
➞ Tennis fans who hope to buy tickets been queuing all night at Wimbledon
14) Some paintings haven't been found yet. They were stolen from the museum.
➞Some paintings which were stolen from the museum haven't been found yet
15) Two languages, Finnish and Swedish, are used in Helsinki. It is the capital of Finland.
➞ Two languages, Finnish and Swedish which is the capital of Finland are used in Helsinki