C. Four times a month.             D. Five times a week.

B

Ladies and gentlemen, I returned to this year in a time machine. In the year 2500, we are able to travel through time to any year in the history of the earth.. This year is your last chance to change your lifestyle to save the earth

Beginning in the middle of the 20th century, a few people were worried about polluting the earth's water and air, but most people did not change their way of life.  Instead, they continued to pour(倒) dangerous chemicals and other waste into lakes and seas, to drive more and more cars and trucks, and to cut down trees.

By the year 2200, the earth's water was completely polluted. Scientists said that in the future there might be too many people on the earth. People could no longer drink water, and they had to use other types of liquids(液体).

So, by the ye ar 2300, there were so many people that food became scarce. There was no water to grow food and all of the fish in the lakes and seas died because of pollution  Terrier wars(战争) broke out between the rich and the poor. Scientists were working very hard to find another planet in space where humans could live on.

By the year 2400, the air was too polluted for humans to breathe. So we had to leave earth But only the rich were able to leave. Where did we go? Nowhere. And everywhere. You see scientists did not find another safe planet, so now we must travel around the universe in our space ships. We are still looking for a place to call our home.

So, it is up to you to change history. There is still hope. You must change your lifestyle now, before it is too late.

49. Which problem is not talked about in Paragraph 2?

A. Water.         B. Air.   C. Lifestyle.        D. Food

50. What's the meaning of 'scarce' in Paragraph 4 in Chinese?

A.昂贵的       B.充足的        C.缺乏的          D.特殊的

51.  Which of the following is TRUE?

A. Only a few people changed their lifestyle in the 20th century.

B. There wasn't enough water for people to drink by the year 2200.

C. All the animals died because of pollution by the year 2300.

D. We found a new home in another planet by the year 2400.

C

Earth Day is on April 22nd. People say thanks to the Earth and learn ways to keep the Earth safe and clean. But saying the Earth is not just for grow-ups. Kids are also taking an active part in it.

The American writer and filmmaker Lynne made a film called Young Voices for the Planet. It lists a lot of stories about different kids who help to keep our environment clean.

Team Marine, US  A group of students an Santa Monica High School started an organization called Team Marine. They tell people why plastic bags are bad for sea animals and environment. In 2011, they successfully made lawmakers(立法者) in their city stop people using plastic bags.