溃疡病急性穿孔的典型体征为
A．胃型
B．高调金属音
C．肠型
D．肝区叩击痛
E．肝浊音界消失
参考答案：E
— Are you going to take part in the speech contest?
— _____ It's too good an opportunity to miss. [ ]
A. No problem!
B. That's for sure.
C. Why me?
D. Why bother?
绝缘体不善于导电是因为它缺少电子．______．
