熔断器一般不做过载保护用,而是做( )电动机的起动和短路保护。
A.长期和重复短时工作制
B.短时工作制
C.重复短时工作制
D.长期工作制
参考答案:D
用所给单词的适当形式填空
1. They refused to give any interviews to __________(journal).
2. Edison won his spurs as an __________(invent) while rather young.
3. The piece of bamboo makes a __________(music) sound.
4. My parents are worried about the __________(safe) of me all the time.
5. The air was __________(pollution) by factory smoke.
一般深孔爆破采用耦合装药,光面爆破,预裂爆破也采用耦合装药。