【C5】A．speedB．frequenciesC．ratesD．proportion

【C12】A．preoccupancyB．preoccupationC．premonitionD．proportion

Energy losses due to _____ occur in every machine.A.speedB.frictionC.impactD.atmosphere

The injection decides the output and therefore, the （) of the engine.A.speedB.sizeC.power

【C17】A．proportionsB．percentagesC．ratesD．ratios

A．speedB．rhythmC．ratesD．ratio

二战时期德国的“三个 S战术”不包括下面哪一项： （)A speedB superiorityC