肾前性急性肾衰竭最常见的原因是（）
A.汞中毒
B.急性肾炎
C.肾内血栓形成
D.尿路梗阻
E.休克早期
参考答案：E
Everyone except Tom and John _____ there when the meeting began. [ ]
A. is
B. are
C. was
D. were
