The conclusion that mechanical efficiency is always （） 100 percent is correct.

[单选题]In a simple mechanical governor, the （）.A . centrifugal force rotates the ball-headB . flyweight centrifugal force is balanced by spring forceC . flyweight centrifugal force is balanced by hydraulic pressureD . speeder spring alone actuates the fuel

[单选题]The mechanical efficiency of an engine （） because losses occur in the form of friction.A . is always less than 100%B . is always more than 100%C . is always equal to 90%D . is always less than 90%

[单选题]Mechanical lubricators for diesel engine cylinders are usually small reciprocating pumps which are （）.A . operated manually once an hourB . operated until the engine has startedC . placed into operation only at maximum loadD . adjustable to meet lubr

[单选题]（） are commonly used in mechanical-hydraulic governor（调速器） to sense engine speeds.A . BulbsB . BulksC . FlyweightsD . Flywheel

[名词解释] 机械性损伤（mechanical injury）

[单选题]The conclusion from the study is not definite；it is just______.A．tentativeB．validC．technicalD．thorough

[单选题]The conclusion is（）the said ship is fit to continue to sail.A . itB . thisC . thatD . what

[名词解释] 机械式传播（mechanical transmissin）

[单选题]We may draw a conclusion that______.A． latchkey children enjoy having such a large amount of time aloneB． latchkey children try to hide their feelingC． latchkey children often watch TV with their parentsD． it's difficult to find out how many latchke

[单选题]No conclusion has been ______ yet.A． achievedB． reachedC． attainedD． arrived