1.An atom consists of a positively charged nucleus which is surrounded by tiny negatively charged particles called electrons.
2.The arrows in the food chain show the direction in which energy is passed form one type of living thing to another.
3.there is a large number of free electrons in a good conductor that allows the flow of electric current.
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4.Conductor allow electricity to pass through them.Insulator do not allow electricity to pass through them. 5.The resistance of a metal wore imcreases if its lenght increases. However ,the resistance of a metal wire decreases if its area increases. 幫幫我.....plz