公称直径为50mm的阀门进行强度试验时,试验最短持续时间为()s。
A.15
B.30
C.60
D.180
参考答案:A
完成句子。
1. ______________, (为了通过考试) he stayed up late preparing for it. (order)
2. It was the second time that ______________. (他给我打电话) (telephone)
3. Finally we ______________ (完成这项任务), although it took a long time. (get)
4. It was a burning cigarette end _____________ (引起火灾) in the city. (cause)
5. People who listen to Hawking's lectures sometimes ______________.(发现很难理解他) (find)
在两次工业革命过程中具有创造性和标志性的成就是
A.富尔顿的汽船和马可尼的电报
B.瓦特的蒸汽机和电子的广泛应用
C.史蒂芬孙的火车机车和贝尔的电话
D.哈格里夫斯的珍妮机和莱特兄弟的飞机