Her electroscope was a metal case with two holes in its side.

她的验电器是一个金属盒子，旁边有两个小孔。

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Figure 4-2 a present - day laboratory version of the electroscope.

图4 - 2就是目前实验室里的验电器样式。

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Figure 4-2 a present - day laboratory version of the electroscope.

图4 - 2就是目前实验室里的验电器样式。

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