题干
The students _____ ￡50 a year to cover the cost of books and stationery.
A：give
B：are give
C：have give
D：to give
答案(点此获取答案解析）
B
A：give
B：are give
C：have give
D：to give
如图，圆弧形桥拱的跨度AB=12米，拱高CD=4米，则拱桥的半径为 ( ) 