John ________ the keys. I cannot see it anywhere.
Đáp án C
“must + have done st”: thể hiện sự phỏng đoán khá chắc chắn về một hành động đã xảy ra trong quá khứ
Ann's encouraging words gave me _________ to undertake the demanding task once again.
In the US the first stage of compulsory education _________ as elementary education.
The local people insisted that the road_________50 cm more so that, in case of flood, they still can travel on it.