Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is best made up from the prompts.
They/ not answer/phone/ this morning, so/ must/ out/.
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.
Chọn C
A. They hasn't answered the phone this morning so they must have been out. (sai thì giữa 2 vế)
B. They didn't answer the phone this morning so they must be out. ( sai vì không đồng nhất thì giữa 2 vế)
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. (sai thì giữa 2 vế)
ð Đáp án C