检维修加油机防爆安全注意事项包括()
A.检维修时先停电.再验电确认;
B.挂警示牌.设置警戒区
C.正确使用检修工具
D.电气维修人员必须持证上岗
参考答案:A, B, C, D
The Japanese people keep up cheerful spirits ________ the world that they can get over the crisis caused by the terrible tsunami(海啸).
A.being convinced
B.convinced
C.to convince
D.having convinced
齿轮传动的主要特点有()。
A.工作可靠性高,但寿命较短
B.要求较高的制造和安装精度,成本较高
C.适宜于远距离两轴之间的传动
D.传动比准确、稳定,但效率较低