Read the following passage and mark th...

Câu hỏi: 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 38 to 45.

A. It may contain uncontaminated microbes

B. It can be studied using radio waves

C. It has already been contaminated

D. It may have elevated levels of ultraviolet light