I can’t remember ________ made the teacher give Mary the permission to leave the class earlier.

－Why did you arrive late?(成都市)－The fog_______ our air flight for about half an hour.

I think my Maths teacher is working hard. He teaches us very .—Yes, but he can’t come today. He doesn’t feel .

Dogs have a very good ______ of smell and are often used to search for survivors in the earthquake.

She ______ have left school, for her bike is still here. [ ]