最常见的咯血原因是（）
A.肺结核
B.支气管扩张
C.心力衰竭
D.肺栓塞
E.支气管肺癌
参考答案：A
一个周角=______个平角=______个直角，过两点能画______条直线，过一点可以画______条射线．
He was educated at the local high school, __________ he went on to Beijing University.
A．after which
B．after that
C．in which
D．in that
