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【简答题】
寿光是闻名全国的蔬菜之乡，一年四季向全国供应优质新鲜蔬菜，如图为寿光三元所建的密封冬暖蔬菜大棚示意图，大棚东西走向，长度为100m，容积为2×10 3 m 3 。大棚顶部长方形塑料薄膜的宽度为10m，空气的比热容为1.0×10 3 J/（kg·℃） （1）天气晴朗的某天，从早上8点到中午12点，棚内温度由15℃升高到35℃，塑料薄膜每平米每小时透过的光能量平均为3×10 4 J。透射到棚内的光能量全部被棚内空气吸收，但由于内外温差较大，所吸收的能量有60%又散失到大棚外。求棚内气体的密度。 （2）阴天时，要在塑料薄膜上面覆盖厚厚的草帘，并改用电炉子为大棚取暖，大棚内气体吸收的热量为电炉子释放热量的 ，要想用2h将棚内的温度由15℃升高到35℃，需要将多少个阻值为24.2Ω的电炉子并连接入到220V的电路中？
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【简答题】插销1,插销2的零件图创建
【简答题】插销的零件图创建
【单选题】Suppose the U.S. offered a tax credit for firms that built new factories in the U.S. Then
A.
the demand for loanable funds would shift rightward, initially creating a surplus of loanable funds at the original interest rate.
B.
the demand for loanable funds would shift rightward, initially creating a shortage of loanable funds at the original interest rate.
C.
the supply of loanable funds would shift rightward, initially creating a surplus of loanable funds at the original interest rate.
D.
the supply of loanable funds would shift rightward, initially creating a shortage of loanable funds at the original interest rate.
【简答题】红外分光光度计的光源主要有 和 。
【单选题】模拟小实验：（如图准备装置）在两只烧瓶里分别充满CO2和空气，塞紧带有温度计和胶头滴管的橡皮塞。再把两只烧瓶放在红外线下照射，观察温度升高的情况。结论：两瓶在相同光线照射下，装CO2的温度较邻瓶高，最大可达4℃。据此完成下列各题。 大气中二氧化碳增多的主要原因是（） ①大量燃烧矿物能源 ②火山喷发 ③过度发展核电 ④过度砍伐森林
A.
①②
B.
①③
C.
②③
D.
①④
【简答题】请对试验结果进行简要分析
【单选题】Suppose the exchange rate of the U.S. dollar was 1.50 British pounds = $1.00 (U.S.) on Wednesday, and on the following Monday the exchange rate was $.75 (U.S.) = 1.00 British pound. Which of the follo...
A.
The U.S. dollar appreciated against the British pound.
B.
The British pound appreciated against the U.S. dollar.
C.
The U.S. dollar depreciated against the British pound.
D.
Both answers B and C are correct.
【简答题】羰基(>C=O),碳-碳双键(>C=C 打浆和加填均能增加纸页的白度。 在纸页内光的散射越厉害,透过纸页的光量就越少,纸的不透明度就越大。
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