1.some factories ofen p______ dirty water into the river.

1.some factories ofen p______ dirty water into the river.
2.will you j_____ us in the game?
3.we ofen keep our classroom clean and t____
4.n______ of us has been to the summer palace.
5.my arents are very p_____ of me.
7.excuse me,have you got any books o____ science?
8.have you ever p____ apples?
9.i am afraid you must p_____ for the lost book.