There are many insects in the world that never do _______ harm to human beings.
—I failed again. I wish I _________ harder. —But you _________.
-What did you do yesterday afternoon?-I went to the bookstore,___ some books and visited my uncle.
The stone on the river bank rolled under her feet; she was _____into the river,and she called out for help.
-Everyone says you are a good student. You are never late for school,are you? -_______.
_____ all the inventions have in common is ______ they have succeeded.