单项选择题 Expansion tank should be used to remove （） from cooling water.

单项选择题 Exhaust temperature increases in all cylinders, the possible cause may be（） (1) increased scavenging air temperature (2) air in fuel pumps and fuel valves (3) fouling of air and gas passages

单项选择题 Excessive clearances in the main or crank-pin bearings will sometimes be indicated by （） before any bearing knock is heard.