Tom took the police to the spot ____ the accident happened．

 It is fairly common in Africa for there______ a group of expert musicians surrounded by others who also join in the performances.

What’s the noise ? It sounds as if it comes from upstairs.   --______. It must be the window-cleaner working , next door.         

We must stop pollution _____ longer. 

 Don’t have horse ______ too fast, it will get tired soon.