保护装置应承受工频试验电压1500V的回路有哪些()
A、110V直流回路对地
B、220V直流回路对地
C、400V交流对地
D、220V交流回路对地
参考答案:A, B
下面说法不正确的是[ ]
A.三角形的面积一定,底和高成反比例
B.长方形的周长一定,长和宽不成比例
C.订阅《少年报》的份数和总钱数成正比例
D.因为圆周长C= πd,所以π与d成反比例
用所给单词的正确形式填空。
1. He is a little (heavy) this year than last year.
2. Hong Kong is _ (warm) than Beijing in winter.
3. —Is this city _ (hot) than that one?
—No , it's (cold) .
4. Miss Liu is (busy) than any other teacher in our school.
5. Tony's dictionary is _ (new) than his sister's.