Câu hỏi:

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 21 to 24.

Is there life on Mars? Many people have (21 )…….about this question. Some writers of science-fiction think of people from Mars as little green creatures. Others imagine "Martians" as monsters with many eyes.

In studying this planet, astronomers have found that life may be possible on Mars. The first (22)……. of this is that Mars has seasons, just like Earth. In other words, Earth's seasons, such as spring or summer, occur on Mars too. Because these seasons exist, it may be possible for (23)…….and other higher (24)….. forms to be found on Mars.

Is there life on Mars? Many people have (21 )…….about this question.