烟烙烙烬IG-541灭火剂是氮气、氩气、二氧化碳混合而成的惰性气体,无色、无味、无毒,不导电,灭火过程洁净,灭火后不留痕迹,不破坏大气臭氧层,对环境无任何影响.
参考答案:对
The driver ______ an ambulance as soon as possible. [ ]
A. gave
B. had
C. called
D. let
离心式压缩机为什么在生产上很少采用串联运行?