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

I have a firm ____in the power of communication, which will smooth away misunderstanding.

There is strong evidence that the          of a father increases the probability that a youngster will use drugs and engage in criminal activity.

The scientific research on how to protect the rare animals is ________. Many scientists are working hard to find new way to raise the animals by man.

In the       of proof , the police could not take action against the man .