Scientists said the smaller the airborne particles, the more ______ they are to cause illness.

One of the English teachers Kate eventually __________ her project to the school board for their approval of the speech contest.

Mr. Tiger insisted that he _______ the money back to his boss but his boss said that he didn’t receive it.

It is the duty of the police to ______ social order.

_______, I don’t like him at all, but it’s strange that he should be so popular among the kids.