[单选题]When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be_____
[单选题]All steel ships are first of all to be surveyed at intervals of approximately one year. These ______deals with a number of relatively minor items which require a yearly check and also require the freeboard marks on the side of the ship to be verified.
[单选题]It is important to use only pure lead and to choose a thickness of wire which is greater than the normal allowable clearance but ____ this amount.
[单选题]What is the normal procedure for safe operation when one of the main engine fuel pumps is to be put out of action?
[单选题]The pressure difference of the gauge on the oily water separator increases greatly, the reason is( ).
[单选题]A large low speed main propulsion diesel engine may become overloaded by_______. I. a heavily fouled hull II. strong head winds and heavy seas
[单选题]If you notice smoke coming from the crankcase exhaust fan outlet of an operating diesel engine, you would suspect ____.