He made another wonderful discovery, （ ） of great importance to science.

Scientists say it may be five or six years （ ） this medicine is tested on human beings.

Are you going to fix the car yourself, or are you going to have it _____?

You needn’t introduce him to me. I’ve met him on several _____.

It is by no means clear （ ） the president can do to end the strike.

I advise them to withdraw （ ）.

—Where is my cell phone? I can’t find it. —Well, you ______ have put it somewhere.

（ ） five hundred people are believed to have drowned.

Before using your new pressure cooker, read the following （ ） carefully.

When Mary paid the bill, she was given a _____ for her money.

It’s vital that enough money_____collected to get the project started.

I recognized John （ ） he entered the room.