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问题 填空题
在复平面内，记复数
3
+i对应的向量为
OZ
，若向量
OZ
饶坐标原点逆时针旋转60°得到向量
OZ
所对应的复数为______．
答案

向量

OZ
饶坐标原点逆时针旋转60°得到向量所对应的复数为

（

3
+i）（cos60°+isin60°）=（
3
+i）（
1
2
+
3
2
i）=2i

，故答案为 2i．

改错题

假定英语课上老师要求同桌之间交换修改作文，请你修改你同

桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。

注意：1. 每处错误及其修改均仅限一词。

2. 只允许修改10处，多者（从第11处起）不计分。

Recently, some college students are busy finding variety of methods to make money during their free time. Some people believed that it is great. In such a competitive society, experience is becoming very more and more important. Doing part-time jobs are a good way to get experience. And it also helps to reducing parents’ financial stress. Others, therefore, argue that students’ duty is nothing but study. On the one hand, part-time jobs may have a negative effect in their studies. On the other hand, students may do something wrong because they are so young to tell good from bad. In my opinion, as soon as they arrange their time reasonably, we are sure to get good grades and work experience.
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填空题

（8分）现有以下四种物质：

A．新制的氢氧化铜[Cu(OH)2]悬浊液

B．碳铵(NH4HCO3)

C．明矾[ KAI(SO4)2·12H2O]

D．熟石灰[Ca(OH)2]请你根据题意，选择恰当的选项用字母代号填空。

(1)检验尿液中是否含有葡萄糖，可使用            ；

(2)要使含泥沙的洪水变澄清，可使用             ；

(3)要中和钢铁厂、电镀厂产生的酸性废水，可使用           ；

(4)给农作物施用氮肥，可使用              。
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