最常见的男性生殖系统结核是
A．肾结核B．输尿管结核C．前列腺结核D．附睾结核E．膀胱结核
参考答案：C
---When did you learn the news that Obama made a trip to Canada as President?
--- _________ was on my return.
A．That
B．It
C．There
D．This
自行车车轮的运动属于（ ）现象。
