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问题 判断题

在工厂供电系统中，二次回路毕竟时器一次电路的辅助部分，因此对供电系统的安全、可靠、优质、经济运行影响不大。

答案

参考答案：错

解答题
已知
a
=(1，2)，
b
=(-3，2)，当k为何值时，
（1）k
a
+
b
与
a
-3
b
垂直？
（2）k
a
+
b
与
a
-3
b
平行？平行时它们是同向还是反向？
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单项选择题

W: Having visited so many countries, you must be able to speak several different languages!
M: I wish I could. But Japanese and, of course English are the only languages I can speak.
Q: What do we learn from the conversation().

A. The man can speak a foreign language.

B. The woman hopes to improve her English.

C. The woman knows many different languages.

D. The man wishes to visit many more countries.
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