声音在15℃的空气中传播的速度是______m/s，真空______（“能”或“不能”）传播声音．

根据句意用所给单词的适当形式填空。

小题1: It is ______________(nature) for a bird to fly.

小题2: It is ____________(polite) to ask a woman her age in western countries?

小题3:Our English teacher likes reading ____________(educate) books.

小题4: I like ____________(lie) on the grass in the sun in spring.

小题5: Do you think noise _____________(pollute) is a terrible problem?