用括号内所给单词的适当形式填空。
1．________(keep) quiet in the library.
2．Don't ________(swim) in the river，please.
3．Please don't ________(be) late for school next time.
4．You should not eat too much ________(meat)．
5．They visited two big ________(factory) last month.
6．There ________(be) some bread on the table. You can have some.
7．Would you like to buy some ________(salt), Mrs. Smith?
8．Both his uncle and his aunt are famous ________(scientist)．
9．How much ________(coffee) is there in the cup?
10．How many ________(watermelon) did you buy yesterday?