Battery
电池
A battery is a box of electricity.
电池是一盒电。
It stores chemical energy and this chemical energy changes into electricity.
它能储存可以转化为电能的化学能。
Can you name the things that need batteries?
你能列举出需要电池的物品吗?
A clock may need a battery.
钟表可能会用到电池。
A car needs a battery to start its engine.
汽车需要电池来发动引擎。
Many things around us are useless without batteries.
我们身边的很多东西没有电池就一无是处。
Do you know that batteries were very huge a long time ago?
你知道很久以前电池的体积很大吗?
People couldn't carry batteries because they were too heavy.
人们携带不了电池,因为它们太笨重了。
So, scientists developed small batteries.
因此,科学家研制出了小型电池。
Now, we can carry them everywhere.
如今,我们去哪里都能带上它们。