Before reaching an ____ ， they had a heated discussion．（agree）
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）．
Do you know________ ________（发生什么）outside just now？