Listen ! Helen is singing in the next room.—It __________ be Helen. She is in Tianjin now.

The purpose of the campaign is to raise the public’s_______ of the dangers of passive smoking.

You can come ______ on Tuesday _______ on Friday, but whichever you choose, please let me know.

He did as much as he _____ her.

If you want to change the world, you have to ______ yourself first.