On the top of the mountain __________.
—I think it is going to be a big problem.—Yes,it could be.—I wonder__________we can do about it.
In the after-class activities,the students had plenty of_________ and gained a lot of practical _________.
She is American,__________she knows little about American history.
The science of medicine,__________progress has been very rapid lately,is perhaps the most important of all the sciences.
Information has been put forward__________more middle school graduates will be admitted into universities.