单项选择题
You must take good care of the drainage cock of the air control systemBecause （） leads scale formed which might malfunction the pilot control valve and other instruments.
A.the temperature B.the rust C.the pressure D.the humidity
单项选择题 You increased the （） to 150 tons that’s why the fuel oil （）.
单项选择题 Worn out ring grooves should be （） to standard dimension after being welded.
单项选择题 With VIT unit the timing of fuel injection of an engine can be regulated automatically according to the （）.
