肺源性的呼吸困难主要是由于（）
A.肺通气、换气功能不良
B.肺活量下降
C.血中二氧化碳潴留
D.缺氧
E.以上均不是
参考答案：A, B, C, D
Kate loves music very much, and he is going to learn how to______.[ ]
A. keep healthy
B. play an instrument
C. play basketball
D. listen to music
无尿是指24小时尿量（）.
A.<100ml
B.<200ml
C.<300ml
D.<400ml
E.<500ml
