人体最主要的造血部位在：（）
A、肝脏
B、骨髓
C、脾
D、血管内
参考答案：B
It is all agreed that a good education doesn't________a good job. [ ]
A. guarantee
B. result
C. depend
D. swear
发生火灾时，送风阀要打开，打开后如何关闭？
