I enjoyed your lecture very much, ______ there were some parts I couldn’t quite understand.

下列词语中划线的字，每对读音都不相同的一组是（ ）

I am familiar with his work and look forward to _____of his view on literary and artistic creation.[ ]

What are you going to do ______you see an old man lying on the road— I am sure to give him a hand.

Boys, don’t swim in the Fengcheng River!—Why not Isn’t it deep enough _____