确定探头声能输出的主要因素是
A．探头大小
B．电压峰强度
C．接收器的放大值
D．增益的大小
E．电流大小
参考答案：B
我国内河货运量仅次于长江，位居第二的航道是（）。
A．珠江
B．京杭运河
C．黄河
D．松花江
Maggie was voted to be the leader of the league that is newly _____, which made her very excited. [ ]
A. put up
B. picked up
C. set up
D. sent up
