在我国，引起咯血的首要病因（）
A.肺淤血
B.二尖瓣狭窄
C.肺结核
D.支气管肺瘤
E.肺栓塞
参考答案：C
水运工程建设项目招标投标活动，应遵循（）的原则。
A.公开
B.诚信
C.平等
D.透明
E.竞争
As angry crowds got into the streets fighting for their basic rights, the local government______the police
to keep order.[ ]
A. called in
B. brought about
C. picked out
D. paid back
