问题：
[单选] In a four-stroke engine the camshaft rotates at （）.
half the engine speed。twice the engine speed。the engine speed。four times the engine speed。
问题：
[单选] In an ordinary diesel engine the fuel injection begins （）
after TDC。before TDC。after BDC。before BDC。
问题：
[单选] In an ordinary four-stroke engine the exhaust valves open （）
after TDC。before TDC。after BDC。before BDC。
问题：
[单选] In each cylinder cover is a large central opening for mounting （）
the indicating cock。the starting valve。air inlet valve。the exhaust valve。
问题：
[单选] In each cylinder cover there are two or three holes for （）
the exhaust valves。the fuel valves。indicator cocks。the fuel pum。
问题：
[单选] In four strokes engine, the cycle of events is completed in four strokes of （）.
the cylinder。the crankshaft。the piston。the cross-head。
问题：
[单选] In general, （） is suitable for delivering small quantities at high pressure.
reciprocating pump。gear pump。centrifugal pump。vane pum。
问题：
[单选] In large marine diesel engines cylinder oils usually contain additives formulated to impart the （） to clean the rings and grooves.
inefficiency。oiliness。detergency。purity。
问题：
[单选] In order to ensure perfect atomization, the fuel oil （） before injection.
has to be cooled。has heated。has preheated。has to be preheated。
问题：
[单选] In order to ensure the safety of the ship and its equipment during UMS operation, certain essential functions （）.
must be provided。may be provided。have provided。can be provided。
