The house was empty when I arrived. They .653/1620The house was empty when I arrived. They ___________.must have gone to bedshould have gone to bedwould have gone to bed.need have gone to bed Giải thíchĐáp án A.Dùng must have + PP để dự đoán điều gì chắc chắn đã xảy ra trong quá khứ.