液压试验时，圆筒的薄膜应力σＴ，不得超过试验温度下材料屈服点的（）与圆筒的焊接接头系数的乘积。
A.90%
B.80%
C.85%
参考答案：A
闪电后3秒钟听到雷声，则打雷处与观察者之间的距离是（ ）
A．610m
B．2040m
C．1020m
D．900m
His expression suggested that he _______ ill, so the teacher suggested that he _______ sent to hospital at once.
A．was; must be
B．is; should be
C．be; be
D．was; be
