【判断题】有的卡尺上还装有百分表或数显装置成为代表的卡尺或数显卡尺提高了测量的准确性
【单选题】马克思主义认为,从实践的活动机制来看,实践是
【判断题】The second-generation technologies include solar heating, biomass, photovoltaics, wind power, solar thermal power stations, and modern forms of bioenergy.
【判断题】有的卡尺上还装有百分表或数显装置,成为代表的卡尺或数显卡尺,提高了测量的准确性
【多选题】以下关于正弦和余弦的傅里叶变换正确的是
A.
f(e j ω 1 t)=2πδ(ω-ω 1 )
B.
f(e j ω 1 t)=2πδ(ω+ω 1 )
C.
f(e- j ω 1 t)=2πδ(ω-ω 1 )
D.
f(e- j ω 1 t)=2πδ(ω+ω 1 )
【单选题】In general, the oil mist detectors include a built-in heating unit and a compact plug for electrical connectionThe function of heating unit is to ()
A.
avoid false alarms as a result of condensing water vapor
B.
avoid danger of frost under very cold weather
C.
reduce the viscosity of the crankcase atmosphere in order to improve the fluidity
D.
keep the temperature of the oil mist detectors in an appropriate range
【简答题】1 include thefts and pilferage, contamination, leakage, sweating and heating, taint, fresh/rain water damage and so on.