单项选择题
A.damage B.form C.dissolve D.contaminate
Acid solution（） in the system can be tested from time t...
单项选择题Acid solution（） in the system can be tested from time to time by putting some on to a piece of lime.
A.strength B.dense C.percentage D.velocity
According to the way the energy of the exhaust gases is...
单项选择题According to the way the energy of the exhaust gases is utilized, pressure-charging can be divided into two main systems, namely, the constant-pressure system and （）.
A.the pulse-phase system B.the pulse Doppler system C.the pulse system D.the pulse interval
About half an hour before the engine is required, cooli...
单项选择题About half an hour before the engine is required, cooling water at （） must be circulated.
A.more than the working temperature B.less than the working temperature C.the working temperature D.the same as the surrounding temperature
