单项选择题
A.Water energy B.Electrical energy C.Chemical energy D.Heat energy
（） is a precaution which contributes to avoiding troubl...
单项选择题（） is a precaution which contributes to avoiding trouble under normal operating conditions.
A.Constant inspection B.Keeping constant load C.Remaining constant temperature D.varying speed
（） are mounted on and bolted to the bed-plate cross gir...
单项选择题（） are mounted on and bolted to the bed-plate cross girders.
A.The crankshaft B.The crankcase C.The guide-ways D.The frames
（） are formed by abrasive particles entering the bearin...
单项选择题（） are formed by abrasive particles entering the bearing and scoring the shaft.
A.Grooves B.Recesses C.Ridges D.Nips
