—Mom,I want to buy this dictionary.It is good and not too________.—Let me see.It is really a useful dictionary.And the price is________.OK,I will buy one for you.
Aron water five days later.
This is______difficult problem that few students can work it out.
.He lives_______in the______village, but he is never_______.
Pollution is a serious problem. Scientists have _______ some good ways to save it.
We can’t put off _____ a plan .