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【简答题】
太阳能热水器以节能、环保等特点为很多家庭所使用，但是如果遇到阴雨连绵的天气，太阳能热水器的不到所需要的温度。为此人们研制出了太阳能、电能两用热水器。小兰家就刚刚安装了一台这样的热水器，如图所示，它的容积为120L。求： （1）若此热水器装满20℃的水，要使水温升高40℃，需要吸收多少热量？ （2）小兰从产品使用说明书中了解到，该电加热器的额定电压为220V，额定功率为2kW。若水箱中的水用电加热器来加热，仍使水的温度从20℃升高到40℃，需要电加热器正常工作多长时间？（假定所消耗的电能全部转化为水的内能） （3）若在上述情况下，电加热器正常工作，实际用了2h，则此电加热器的效率是多少？
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【简答题】汽车的行驶阻力包括滚动阻力、空气阻力、加速阻力和上坡阻力,其中( )和( )是在任何行驶条件下均存在的。
【单选题】What does the author tell us about Dr. Granich and his collegues and their trials?
A.
They use data from some African countries and other poor countries.
B.
They want to find out whether the alternative approach can function.
C.
The first-line antiretroviral drugs are effective in curing patients.
D.
Their study is to let the patients have no symptoms of AIDs.
【简答题】汽车的行驶阻力包括 、 、 和 等。
【单选题】Is there no end to the Drug Plague? Last year, our nation's capital passed the murder-a-day mark, and the number of homicides is now up some 50 percent from that level. More than half of these killing...
A.
There Is No End to the Drug Plague
B.
Let's Get Tough with Drug User
C.
We Must Crack Down on Drug Supplies
D.
Everyone Is A Victim of Drug Use
【单选题】Is there no end to the Drug Plague? Last year, our nation’s capital passed the murder-a-day mark, and the number of homicides is now up some 50 per cent from that level. More than half of these killin...
A.
There Is No End to the Drug Plague
B.
Let’s Get Tough with Drug User
C.
We Must Crack Down on Drug Supplies
D.
Everyone Is A Victim of Drug Use
【简答题】汽车的行驶阻力包括滚动阻力、空气阻力、加速阻力和（）阻力。
【单选题】深圳某企业本期期初资产总额为18万元，本期期末负债总额比期初减少l万元，所有 者权益比期初增加3万元。该企业期末资产总额是（ ）万元。
A.
19
B.
21
C.
20
D.
18
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