问题补充：
There is not enough oil in the world now. As time goes by ,it becomes less and less ,so what are we going to do when it runs out? Perhaps we will go back to use horses ,carriages and bicycles .
In the Second World War ,some people didn＇t use gas made from petroleum （石油）in their cars .They made gas from wood and plants instead . The cars didn＇t go fast ,but they ran ,so this was better than nothing. However, in the future, we can＇t cut down all our trees to make gas; we need our trees for other things, too.
Besides different types of gas, we can also use electricity(电)to run our cars but first we must make the electricity ！Some countries have coal and they make electricity with that, but we might not always have coal, either. Other countries have big ,strong rivers and they can use the power of water to turn turbines(涡轮机) and make electricity more easily and cheaply.
We are also able to get power from the ocean tides. We put turbines into the mouth of the river .Then the tide comes in ,the water turns the turbines and then it goes out ,it turns them again.
Which of these ways will be used to run our cars in the future?
【小题1】When might people have to go back to using horses and carriages?A．When they are poorB．When they run out of oilC．When they need more exerciseD．When there aren＇t any big trees in the world【小题2】How many ways are suggested to make electricity in the passage?A．2B．5C．4D．3【小题3】The passage is mainly about .A．how to run our carsB．what to do when oil runs outC．different types of gasD．the way to make electricityB
答案：
(答案→)B
解析：
【小题1】根据There is not enough oil in the world now.及下文描述可知选B。
【小题1】根据短文描述主要介绍三种发电方法，火力发电，水力发电和利用海洋潮汐，故选D。
【小题1】根据so what are we going to do when it runs out?及下文描述可知本文主要讲的是当石油用完时，我们怎么办？故选B。
