One hertz is equal to one ( )

A:cycle per centimeter B:cycle per meter C:cycle per second D:cycle per eV

钻镗循环的深孔加工时需采用间歇进给的方法，每次提刀退回安全平面的应是（）。（SIEMENS系统）

A:CYCLE81 B:CYCLE82 C:CYCLE83 D:CYCLE84

下列指令中，（）是毛坯切削循环指令（SIE州田NS系统）。

A:CYCLE93 B:CYCLE95 C:CYCLE96 D:CYCLE97

The time necessary to complete a project is referred to as ______.

A:implementation time B:life cycle C:operations cycle D:production cycle

All of the following are true about the product life cycle EXCEPT:

A:It is collection of generally sequential, non-overlapping product phase B:The last product life cycle phase for a product is generally the product’s deterioration and deat C:Generally, a project life cycle is contained within one or more product life cycle D:Generally, a project life cycle contains one or more product life cycle

产品生命周期英文是（）。

A:production cycle B:product time C:product．life cycle D:goods cycle time

Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because ____.

A:bearing pressure in a four-stroke\cycle acting single diesel engine is continuallyreversed B:bearing pressure in a two-stroke\cycle single acting diesel engine is continuallyreversed C:the maximum bearing pressure is higher in a single acting two-stroke/cycle dieselengine D:two-stoke/cycle diesel engines require more complicated lubrication piping

Which of the following statements is true regarding the installation of piston rings on two-stroke/cycle, diesel engines as compared to four-stroke/cycle, diesel engines? .

A:In a two-stroke/cycle engine, the rings run hotter, requiring the end gap to be greater B:Some provision must be made in a two-stroke/cycle engine to keep the rings from bindingin the ports C:No gap is required to exist between the ends of the ring when cold in a two-stroke/cycleengine, but a small gap is required in a four-stoke/cycle engine D:The gaps should be staggered on either side of a piston in a two-stroke/cycle engine,while staggering is not necessary in a four-stroke/cycle engine

The size of the exhaust valve opening is __________________.

A:most critical in a four-stroke cycle diesel engine B:most critical in a two-stroke/cycle diesel engine C:most critical in a four-stroke/cycle diesel engine if it is turbocharged D:of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cyclediesel engine