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【简答题】
一斜射到光滑平面上，入射光线与平面的夹角是60°，则入射角是______．当入射角增大15°时，反射光线与入射光线之间的夹角是______．
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【单选题】—Could you tell us _____ to travel from Earth to Mars by spaceship? —It takes months, I think. [ ]
A.
how far it takes
B.
how long it takes
C.
how long does it tak
D.
how soon does it take
【简答题】七选五 Crossroads International 1. How does Crossroads work? Crossroads is a resource network.We take goods Hong Kong doesn't want and give them to people who badly need them.We collect those goods and g...
【简答题】主键,( )KEY,用于唯一标识某条记录,作为主键的值必须唯一,且不能为( ),主键可以是单一字段,也可以是多个字段的组合,每个数据表最多能有( )个主键约束
【单选题】—Do you know if Linda is willing to take charge of the program? — ______, does it?
A.
It takes no time
B.
It counts for nothing
C.
It doesn't hurt to ask
D.
It doesn't make sense
【简答题】与其他成形方法相比,塑性成形使金属 、 、 提高。
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