第二节 阅读短文，从每题所给的A，B，C三个选项中，选出最佳选项回答问题。(共5小题，计10分)

　　Hundreds of years ago, life was much harder than it is today. People didn't have modern machines. There was no modern medicine, either.

　　Life today has brought new problems. One of the biggest is pollution. Water pollution has made our rivers and lakes dirty. It kills our fish and pollutes our drinking water. Noise pollution makes us talk louder and become angry more easily. Air pollution is the most serious kind of pollution. It's bad to all living things in the world.

　　Cars, planes and fACTories all pollute our air every day. Sometimes the polluted air is so thick that it is like a quilt over a city. This kind of quilt is called smog (烟雾，雾霾).

　　Many countries are making rules to fight pollution. FACTories must now clean their water before it is thrown away, and they mustn't blow dirty smoke into the air. We need to do many other things. We can put waste things in the dustbin(垃圾桶) and not throw it on the ground. We can to go work by bus or with our friends in the same car. If there are fewer people driving, there will be less pollution.

　　Rules are not enough. Every person must help to fight pollution.

　　46. Hundreds of years ago, life was much harder than it is today because ____.

　　A. there were not any modern machines

　　B. there was no modern medicine

　　C. both A and B

　　47. What is one of the biggest problems in today's life?

　　A. Water pollution

　　B. Air pollution

　　C. Pollution

　　48. The most serious kind of pollution is ____.

　　A. noise pollution

　　B. air pollution

　　C. water pollution

　　49. FACTories must clean their water ____.

　　A. before they are thrown away

　　B. when they are thrown away

　　C. before it is thrown away

　　50. From the passage we know that ____.

　　A. people are making rules in order to fight pollution

　　B. today people don't have to talk to each other in a loud voice

　　C. a few years ago, there was no smog at all