Athletics were his favourite sport when he was a high school student.

A. motivated

A. You had better sit down.

B. You are allowed to sit down.

C. You are necessary to sit down.

A. It would be a lovely room if its view were difficult.

B. Provided the room had a difficult view, it would be a lovely room.

C. But for its difficult view, it would be a lovely room.

D. Unless the room has a difficult view, it won't be a lovely room. 

A. When I knew that my mother's vase was missing, I picked some roses.

B. It was not until I had picked some roses did I notice my mother's favorite vase was missing. 

C. Only when I had picked some roses that I noticed my mother's favorite vase was missing.

D. I picked some roses and only then did I notice that my mother's favorite vase was missing.

A. to

A. to travel