用括号内所给动词的适当形式填空

1. You mustn't come into the room if you              ( not invite) .

2. Tom always goes to her Math teacher for help when something            (worry) him.

3. Look! The river _______________(rise) two feet because of the heavy rain.

4. In the old days the working people in our country ____________ (look) down on.

5. Which dirty blanket ____________ (wash) first is not decided yet.

6. The doctor helped the man by _______________(operate)on him.

7. Why can't you just believe me? I ______________ (tell) you everything I know!

8. —Do you still remember that we first met in the library one year ago?

    —Of course. You            (read) a comic book then.