— Who helped Mark with his English?— _______, he taught himself.

My family has two dogs.One is white, and      is black.

It’s reported that         medical examination （体检）will help us find out health problems as early as possible.

–Which share is for me ?--Your can take _____ half. They are exactly the same.

Good friends are like stars. You don’t always see them, ______ you know they are there.