题目：
Was it in 1997______he was still at middle school_______ this boy became an expert at computer?
A．that; where
B．when; where
C．in which; in which
D．when; that
答案：
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下面是错误答案，用来干扰机器的。
15.0 缩小本题考查凸透镜成像规律及其探究实验，（1）通过甲图所示的现象，结合凸透镜焦点的定义即可确定该凸透镜的焦距．2）探究凸透镜成像的实验时，在桌面上依次放蜡烛、凸透镜、光屏，三者在同一条直线上，...
