用____________和______________的方法都可以使物体带电。

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问题填空题

答案

摩擦感应或接触起电

题目分析：三种起电方式：摩擦、感应和接触起电

点评：难度较小，牢记三种起电方式：摩擦、感应和接触起电

选择题

In ancient times, dogs were mainly ______helping people hunt( 打猎) .Now they are more useful-they can help the blinds, search for the bad eggs,...

A．bad for

B．used to

C．used for

D．good at

判断题

气体电离的必要条件是有电场或热能的作用。( )