单词拼写。
1 ．Scientists have made many important_______ (发现)．
2.An____ (突然的)change of policy made everything up.
3 ．The store sells agricultural______ (产品)．
4.I keep my reference books near my desk for_______ (方便)．
5. He ate a light lunch in____ (期望)of a good dinner.
6. He likes inventions and he has applied for a p____ .
7. I've never seen so much m_____ and disorder.
8. It's an interesting idea but there are many p _____ difficulties.
9. As _____ world is essential to economic growth.
10. He goes to visit his grandparents not regularly but o _____ .