We must keep our room clean. Dirt and disease go _____ you know.

_________ is he—He is Andy’s father.

My mother didn’t ____ us leaving Kunming at once, so we had to stay there for ____ two days. [ ]

I often watch CCTV-9, ________ I have learned a lot of new words and expressions.

My friend ______ from the UK. She studied at Oxford for four years, during which we communicated with each other on the Internet.