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问题 单项选择题

对于半导体热敏电阻的特点，说法错误的是（）。

A.非线性大

B.对环境温度敏感性大

C.测量时不易受到干扰

D.灵敏度较高

答案

参考答案：C

填空题
根据句意，从方框中选择合适的单词并用其适当形式填空。
shelf, two, put, watch, be
1. —Where's your study?
    —It's on the _____ floor, next to my bedroom.
2. There are two _____ in my study. There are many books on them.
3. Children like _____ TV a lot. But it is not good for their eyes.
4. There _____ a knife, a pen and two pencils in the box.
5. Our math teacher often _____ his keys in the drawer
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单项选择题

为“教师”表的职工号字段添加有效性规则：职工号的最左边三位字符是110，正确的SQL语句是

A．CHANGE TABLE教师ALTER职工号SET CHECK LEFT(职工号，3)=“110”

B．ALTER TABLE教师ALTER职工号SET CHECK LEFT(职工号，3)=“110”

C．ALTER TABIE教师ALTER职工号CHECK LEFT(职工号，3)=“110”

D．CHANGE TABLE教师ALTER职工号SET CHECK OCCURS(职工号，3)=“110”
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