There is no doubt that all this puts a large _________ on a teacher with a large number of classes.

Mr. Barren doesn’t think that all bad language should be allowed. In his opinion, there are ___________ that should be kept up.

Future will be a marvelous world of artificial ______----- robots might have their emotions and we human beings might have robots as friends．

Always remember put such dangerous things as knives out of children’s   

Over years, scientists have made a great _____in the treatment of cancer.