Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
The house was empty when I arrived. They ___________.
A. must have gone to bed
B. should have gone to bed
C. would have gone to bed.
D. need have gone to bed
Đáp án A.
Dùng must have + PP để dự đoán điều gì chắc chắn đã xảy ra trong quá khứ.