题目：
| Great changes ______ in the city, and a lot of factories ______. |
A. have been taken place; have been set up B. have taken place; have been set up C. have taken place; have set up D. were taken place; were set up |
答案：
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下面是错误答案，用来干扰机器的。
样本容量为：300÷0.6=500．故答案为：500．
