【单选题】下列关于铀矿的描述不正确的是()
C.
地壳中总埋藏量比金、银少,化学性质不活泼,开采相对困难
【判断题】渗碳体是铁与碳形成的金属间化合物,其含碳量为6.69%,质硬而脆,耐蚀性强,经4%硝酸酒精浸蚀后,渗碳体任呈亮白色,而铁素体浸蚀后呈灰白色,由此可区别铁素体和渗碳体。
【判断题】Decentralized vacuum pump is suitable for filling machine internal space is not enough to install centralized vacuum pump, gasoline sales volume is not large gas stations.
【判断题】渗碳体是铁与碳形成的金属化合物,碳含量是6.69%,具有复杂的晶体结构。
【单选题】With a purely resistance load the voltage and current are in phase, giving a power factor of _____.
【单选题】Why is it desirable to operate paralleled AC generators at the same power factor?()
A.
Circulating currents are kept to a minimum
B.
Field excitation losses are kept to a minimum
C.
Generator rotors will have a lesser tendency to hunt
D.
Because a power factor increase will decrease kilowatt output
【单选题】7个月婴儿,高热、咳嗽6天,气促3天,今日抽搐3次。已接种卡介苗。查体:体温39℃,脉搏180次/分,呼吸70次/分。处于昏睡状态,面色发绀,双目凝视。前囟稍饱满,双肺散在细湿罗音,肝肋下3.5cm,颈软,克氏征阴性,巴氏征阳性。血白细胞9乘以十的九次方/L,中性粒细胞0.35,淋巴细胞0.65。脑脊液:外观清,蛋白定性阴性,细胞数2乘以十的六次方/L,糖3.7mmol/L,氯化物118mmol/...
【单选题】Policies are also an important factor for the car market ______ the purchasing power of people.