Which of the listed items should be secured before performing any maintenance on a solenoid operated air start valve?（）

If the engine is naturally aspirated, or is a small high-speed type with a centrifugal turbocharger, the period of valve overlap（）,ie when both valves are（）, will be and the exhaust valve will close some 10°top dead canter（）.

(单项选择)Most wage claims are settled by ____________.

“Full speed ahead” and “Full speed astern” are（）given by the officers or the pilots.

Camshafts are usually driven by timing gears or （）.

Most hydraulic steering gears are fitted with relief valves which（）

The period when both inlet valves and exhaust valves are open is referred to as （）.

Sometimes lights are（）by fog，haze，dust，smoke，or precipitation which may be present at the light，or between the light and the observer，and which is possibly unknown by the observer.

Fire alarm system thermostats are actuated by（）.

The solenoid valve can be typed as a（）

In the starting system, the automatic valve is controlled by（）, and the cylinder start valves are controlled by（）

Compensated flow control or constant flow valves are used in hydraulic systems to（）