Mark the letter A, B, C, or D on you...

Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions from 45 to 46.

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

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

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

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