输卵管妊娠最常见的病因为：
A．输卵管手术
B．输卵管炎症
C．放置IUD
D．子宫内膜异位症
E．输卵管发育异常
参考答案：B
The teacher asked Ben ____________ a difficult question in class.
A．answer
B．answering
C．to answer
D．answered
塑料制个人用烟盒
