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问题 计算题

把高温铁块投入质量为10kg、温度为10℃的水中，水吸收的热量是2.1×106J，则水的温度会升高多少？［不计热损失，已知水的比热容c水=4.2×103J/（kg·℃）］

答案

解：△t＝Q吸/cm＝2.1×106J/（4.2×103J/（kg·℃）×10kg）＝50℃

综合

读“大气的热力作用图”和“太阳高度与太阳辐射经过大气路程长短的关系示意图”，回答下列问题。

（1）图中各序号表示的作用过程是：

①__________辐射，    ③_________辐射，    ⑤____________辐射。

（2）冬天多云的夜晚比晴朗的夜晚要暖和一些，其原因是________________________________________________________________________________________。

（3）在低纬地区，太阳高度角较大，太阳辐射经过大气的路程较______，被大气削弱得较______，最后到达地面的太阳辐射较_______。

（4）下列自然现象是图中大气的什么作用的结果

① 白天多云时，气温比晴天低_______________作用

② 地球上观察晴朗白天的天空是蔚蓝色的_______________作用
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单项选择题

Both Writewell and Express provide round-the-clock telephone assistance to any customer who uses their word-processing software. Since customers only call the hot lines when they find the software difficult to use, and the Writewell hot line receives four times as many calls as the Express hot line, Writewell’s word-processing software must be more difficult to use than Express’s.
Which of the following, if true, most strengthens the argument above

A．Calls to the Express hot line are almost twice as long, on average, as are calls to the Writewell hot line.

B．Express had three times the number of word-processing software customers that Writewell has.

C．Express receives twice as many letters of complaint about its word-processing software as Writewell receives about its word-processing software.

D．The number of calls received by each of the two hot lines has been gradually increasing.

E．(E) The Writewell hot-line number is more widely publicized than the Express hot-line number.
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