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【简答题】
( 3 ) 回归平方和是指 ( ) 。 A . 被解释变量的实际值 y 与平均值 的离差平方和 B . 被解释变量的回归值 与平均值 的离差平方和 C . 被解释变量的总变差与剩余变差之差 D . 解释变量变动所引起的被解释变量的变差 E . 随机因素影响所引起的被解释变量的变差 A.B.C.D.E. E
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【单选题】听力原文：W: Hello, John, how are you feeling now? I hear you've been ill. M: They must have confused me with my twin brother Rod. He's been sick a week, but I've never found better in my life. What do we ...
A.
He is taking care of his twin brother.
B.
He has been in his perfect condition.
C.
He must be feeling ill in his health.
D.
He is worried about Rod's health.
【单选题】Many questions have been answered by John. He must have previewed the lessons last night, ____ he?
A.
needn’t
B.
hasn’t
C.
didn’t
D.
mustn’t
【简答题】John must have been busy yesterday,otherwise he ____________________(come) to the party.
【单选题】下 列 表 达 式 错 误 的是
A.
甲烷的电子式：
B.
氮原子的 L 层电子的轨道表示式：
C.
硫离子的核外电子排布式： 1s 2 2s 2 2p 6 3s 2 3p 4
D.
碳 •12 原子： 12 6C
【单选题】— Where is John? — He _____ in the library.
A.
should be
B.
must be
C.
can be
D.
must have been
【简答题】目前数码相机使用的成像芯片主要有 芯片和CMOS芯片两大类。
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