--What about the protection? ---Let’s keep the surface ____ dirty by putting a cover over it.

I firmly believe _____ he said at the meeting was right.

.I dislike__________when I am left alone to start a conversation with a stranger.

_____ the government agrees to give extra money , the theatre will have to close.

 No one knows exactly when our ancestors started talking，but new evidence suggests  _______might have happened a long time ago．