Mark the letter A, By Cy or D on...

Câu hỏi: Mark the letter A, By Cy or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

A. We shall know more about our sleep if we spend more than one-third of our lives sleeping

B. We know relatively little about our sleep; as a result, we spend about one-third of our lives sleeping

C. Despite spending about one-third of our lives sleeping, we know relatively little about our sleep

D. We spend about one-third of our lives sleeping so that we know relatively little about our sleep