They expected that they could solve the problem by________（they）．
________（polite），he drove the old man out of the room and shouted at him angrily．
Be careful to cross the street when we meet heavy________（traffic）．
My mother can’t sleep well，and sometimes she even stays________（wake）the whole night．
Is it possible for us human beings to leave all the animals in the________ ________（自然环境）？
Some of my friends are interested in________ ________（集邮）．
