咳嗽伴声音嘶哑常见于（）咳嗽伴鸡鸣样回声常见于（）
A.气管异物
B.喉癌
C.百日咳
D.慢性支气管炎
E.支气管扩张症
参考答案：B,C
—Thanks a lot, Mr. Wang. I don't know how to ________ the help you gave me during my stay here.
—It's my pleasure. Welcome to China again when you have time. [ ]
A. pay off
B. pay back
C. pay for
D. pay to
水静力学基本方程式适用于绝对静止状态下的（）液体。
A.不连续
B.流动
C.静止
D.连续均质
