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举一反三
【单选题】钳工师傅在刃磨麻花钻时,要经常在水槽内进行冷却降温,其目的是:
A.
防止钻头因为磨削温度过高烫伤手掌
B.
防止钻头因为磨削温度过高而变形
C.
防止钻头因为磨削温度过高而使其磨削后硬度降低
D.
使钻头淬火，提高其硬度
【单选题】设有一个关系EMP(职工号，姓名，部门名，工种，工资)，若需查询不同部门中担任“钳工”的职工的平均工资，则相应的SELECT语句为： SELECT部门名，AVG(工资)AS平均工资 FROM EMP GROUP BY (1) HAVING (2) 将职工号为“23115”、姓名为“李军”、部门名为“硬件测试部”的元组插入EMP关系中的SQL语句为：Insert (3) (2)
A.
工种=’钳工’
B.
’工种=钳工’
C.
’工种’=钳工
D.
工种=钳工
【单选题】In the wake of 11 September, Visionics, a leading manufacturer, issued a fact sheet explaining how its technology could enhance airport security. They called it "protecting civilization from the faces...
A.
any way, the face-recognition technology is good enough to frighten the terrorists
B.
the industry will have to recognize the real situation and work hard to improve the technology
C.
all the claims are premature
D.
we must not expect too much