Have you read a book on sea _______?
1.The teacher's ________is that we should always use English in our daily life.
2.Have you read a book on sea __________?
3.We have little ________to win.
4.In the 19th century,gold was _________in California.
5.The new rules become __________ in the next few days.
6.China has experienced a series of ___________ since 1978.
7._________is a kind of useful subject in the university.