Both his parents look sad. Maybe they ________ what happened to him.

Today, we’ll discuss a number of cases __________ beginners of English fail to use the language properly.

－Dad, may I watch TV－No, you can’t. You _______ finish your homework first.

None of us _____ running, but we all like swimming.

_______ great man Huang Furong is! He lost his life while savingthe students in the Yushu earthquake.