1) electron is an example of a) negative charge b) positive charge c) neutral chrage 2) proton is an example of a) negative charge b) positive charge c) neutral chrage 3) like charges a) attract b) repel 4) un-like charges  a) attract b) repel 5) charges are a) quantized b) negative and positive c) all of the above

排行榜

視覺風格

選項

切換範本

恢復自動保存: ?