Be polite . You _____ talk to the old like that ! —Sorry , I won’t .

______stopping polluting the earth______hope to live in a better environment．

I think____________ necessary _____________ to take more exercise.

Three problems are too hard to . Will you give me some advice? —-There are many ways. The mostt important is to have a careful plan.

Please call me ______ 289-4568.[ ]