1.Did you have a good summer holiday?
2.My hometown has become more and more beautiful.
3.Where have you been?
4.there were so many people that I couldnt find a proper place to take photos.
5.there goes the bell.
6.I havent seen him for a long time.
7.You have taken part in some volunteer activities during the summer holidays, havent you?
8.What a wonderful experience!
9.Could you tell me something about Chinese teenagers in the past?
10.Can you describe it in detail?
11.Parents couldnt afford an education for their children.
12.They worked day and night and never had enough food to eat.
13.The government gives support to poor families, so children can get a good education.
14.A big family were crowded in a small house.
15.People kept in touch with their friends and relatives far away mainly by letter or telegram.
16.Beijing has made rapid progress and it has already succeeded in hosting the 2008 Olympic Games.
17.I think it is important to remember the past, live in the present and dream about the future.
18.I have just called you, but you werent in.
19.Ive never been there before, but I dont want to go there any more.
20.Because there were too many people. We got lost and couldnt find each other.
21.Have you found him yet?
22.He has probably gone home.
23.-I really hate to go to such a place. So do I.
24.It seems that their living conditions were not very good.
25.Great changes have taken place in China in recent years.
26.-No one likes Little Emperors.   
Neither do my parents.
27.They are very strict with me.
28.It says the world has a population of 6.5 billion.
29.仁爱版英语It is increasing by 80 million every year.
30.China has the largest population.
31.Whats the population of the U.S.A.?
32.There is less living space for each family.
33.Its difficult for lots of people to find jobs.
34.We are short of energy and water.
35.Most cities are more crowded than before.
36.The traffic is much heavier.
37.So far, our government has taken many measures to control the population.
38.The population problem is still serious in China. We still have a long way to go.
39.I cant go shopping in big stores unless I travel for a couple of hours.
40.Sometimes it is hard to see my friends because they live so far away.
41.You will get used to it very soon if you come.
42.Its a wonderful place to live.
43.You must come for a visit.
44.Once they find people in need, they decide on suitable ways to help them.
45.Can the homeless people get enough food and medical treatment?
46.The program also provides them with houses.
47.It trains them so that they can find jobs again.
48.The world has changed for the better.
49.The flowers and grass have gone.
50.There are several chemical factories pouring waste water into the stream.
51.How long have you been like this?
52.The chemical factory produces terrible gas. The bad air makes my chest hurt.
53.The makes too much noise and I cant sleep well at night.
54.Im always in a bad mood because I cant stand the environment here.
55.Anyway, I hope the government will solve this problem soon.
56.Air pollution is harmful to peoples health.
57.People who work and live in noisy conditions go deaf easily.
58.It not only disturbs others but also does great harm to peoples hearing.
59.Many countries are trying to solve all sorts of environmental problems, including noise pollution.
60.I can cause sore eyes and breath problems.
61.It makes our environment dirty.
62.Soil pollution causes unhealthy food.
63.Noise pollution can make people deaf.
64.It makes people feel terrible and is especially bad for the eyes.
65.With less pollution, our planet will become greener and our health will be better.
66.We shouldnt leave rubbish here and there.
67.Dont walk on grass or pick flowers.
68.Everyone should care for wild animals and plant more trees.
69.We should do everything we can to protect the environment.
70.People have cut down too many trees, As a result, a lot of rich land has changed into desert.
71.Tress can stop the wind from blowing the earth away.
72.A lot of water can be saved by forests.
73.They can also prevent the water from washing the earth away.
74.Can you tell us what you are doing there?
75.We should use both sides of the paper and reuse plastic bags.
76.I think recycling can not only protect the environment but also save money.
77.We encourage students to collect waste paper and soft drink can.
78.We sort them so that they can be recycled.
79.Everyone is supposed to do so.
80.You ought to turn off the lights when you leave a room.