We should study hard, because ________ can change our life.
A.discussion B.introduction C.knowledge D.difference
The machine was very dirty, but Peter and Mark managed ________ it.
A.to clean B.clean C.cleaning D.cleaned
After three hours' discussion, they finally agree ________ a new cinema in this town.
A.to watch B.watch C.to build D.build
Children are warned not________ in the deep river, because it is too dangerous.
A.to swim B.swim C.swimming D.swam
Lily’s parents always encourage her ____out her opinions.
A. speak B. speaking C. to speak D. spoken
I happened ________ an old friend on the street. We haven't seen each other for years.
A.meeting B.met C.to meet D.meet
