A two stroke diesel engine exhaust temperature will be lower than a four stroke diesel engine of the same displacement because the _____. ① MEP is lower and the scavenging air is cooling the exhaust gases ② valve overlap in a four stroke
A. ①
B. ②
C. ① and ②
D. Neither ① nor ② is correct
投资的增加会使总需求________,总需求曲线________移动,同时经济处于经济周期的________阶段。
A. 下降;向右;经济增长
B. 上升;向右;经济增长
C. 下降;向左;经济衰退
D. 上升;向右;经济衰退
E. 上升;向左;经济衰退
关于活塞销的材料、结构与表面处理,正确的有________。I.铸铁II.合金钢III.中空结构IV.实心结构V.表面退火VI.表面淬火
A. III+IV+VI
B. I+II+III
C. IV+V+VI
D. II+III+VI
When under maneuvering conditions with the machinery being manually operated the control unit or console should be
A. automatically controlled
B. continuously manned
C. off power
D. continuously unmanned