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问题 判断题

分类数据可以比较相互之间大小。

答案

参考答案：错

解析：分类变量没有数值特征，所以不能对其数据进行数学运算。分类数据只能用来区分事物，而不能用来表明事物之间的大小、优劣关系。

填空题



After its (1) to the (2) in 2001, China has taken steps towards opening up its (3) . As a condition for joining the WTO, China (4) itself to a (5) of trade liberalization, including the reduction of tariffs on cars and agricultural products. These tariffs reductions are both (6) and there is (7) for China to (8) at a faster pace.
A (9) of (10) and a more rapid and profound reduction of import tariffs would (11) of those Chinese consumers who would (12) imported products at lower prices. Second, a higher (13) into China would take away much upward pressure on the Renminbi and provide a true and lasting (14) to solving current global (15) . Indeed, even a modest (16) in the opening-up process would go a long way towards solving the problem.
The opening up of China’s markets to international competition should (17) deep reforms. Banks should be recapitalized, bad loans provisioned fully and state-owned companies’ runaway indebtedness (18) . Only when real progress in these areas is made should China begin to consider a reform to its (19) . Doing it any earlier would be highly (20) .
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选择题
如图所示，两根相距为l的平行直导轨ab、cd、b、d间连有一固定电阻R，导轨电阻可忽略不计；MN为放在ab和cd上的一导体杆，与ab垂直，其电阻也为R；整个装置处于匀强磁场中，磁感应强度的大小为B，磁场方向垂直于导轨所在平面（指向图中纸面内）；现对MN施力使它沿导轨方向以速度v（如图）做匀速运动；令U表示MN两端电压的大小，则（　　）

A．U=vBl，流过固定电阻R的感应电流由b到d

B．U=vBl，流过固定电阻R的感应电流由d到b

C．U=vBl，流过固定电阻R的感应电流由b到d

D．U=vBl，流过固定电阻R的感应电流由d到b
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