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 is best made up from the prompts.

A. They hasn't answered the phone this morning so they must have been out.

B. They didn't answer the phone this morning so they must be out.

C. They didn't answer the phone this morning so they must have gone out.

D. They hasn't answered the phone this morning so they must go out.