问题
A tsunami(海啸) _____ in some southern Asian countries in December, 2004. As a result, _____ homeless people had to stay in the open air.
A:has happened/ thousands of
B:happened/ thousands of
C:has happened/ about twelve thousand of
D:happened/ twelve thousands;
B:happened/ thousands of
C:has happened/ about twelve thousand of
D:happened/ twelve thousands;
正确答案是：
