Ⅳ. Translation.
1. 人们每年砍掉数百万棵树来生产家具。(millions of)
.
2. 在日常生活中，我们要尽最大努力节约用水。(do one's best)
.
3. 他们正在讨论如何与空气污染做斗争。(fight against)
.
4. 用微信交谈对于我们来说很方便。(convenient)
.
5. 我们无法想象生活在没有氧气的世界。(imagine)
.

Ⅳ.
1. People cut down millions of trees every year to produce furniture.
2. In our daily life, we should do our best to save water.
3. They are discussing how to fight against air pollution.
4. It is convenient for us to talk on WeChat.
5. We can't imagine living in a world without oxygen.

Ⅴ. Writing.
梧桐山（Wutong Mountain）之所以被称为深圳的“市肺”，是因为这里有茂盛的植被，空气也是深圳最清新的。因此，保护梧桐山的树木，文明游览梧桐山是每位游客应尽的责任和义务。请你根据下面的内容，为梧桐山写一篇游览细则。（80词左右）
1. 我们一定要保护好山上的树木，不能砍伐，不能在树上写字；
2. 在游览梧桐山时，我们不能带火种进山，也不能在山上生火；
3. 发现山上发生火灾，要立刻报警。
提示：火种 fire；生火 set a fire；报警 call the police

Wutong Mountain Visiting Rules
1. Protect trees: Do not cut down trees or write on them.
2. No fire: Do not bring fire into the mountain or set a fire.
3. Emergency: If a fire breaks out, call the police immediately.
Please follow these rules to keep Wutong Mountain green and safe.

1 Cloze test.
Long ago, there were not so many people on the Earth. There are no cars. There were many trees and the Earth was 1. Later, the cities 2 bigger and bigger. And there was a lot of rubbish soon.
We are hurting the Earth 3 we throw our rubbish anywhere. The land is not very clean now. We are hurting the Earth when we throw our rubbish into the water, when we drive our cars and when we 4 trees. The trees help 5 our land and air clean. Now we do not have as many trees 6 we did before. Now the animals do not have as much space as they did before.
There are many things we can do 7 hurting the Earth. We can recycle some of our rubbish. We can plant more trees to keep the air 8. We can put up signs that 9 people to keep the Earth clean. It may 10 a long time to clean up our Earth and needs everyone’s help.
() 1. A. dirty
B. clean
C. dry
D. wet
() 2. A. came
B. turned
C. went
D. grew
() 3. A. what
B. when
C. how
D. where
() 4. A. plant
B. use
C. cut down
D. burn
() 5. A. keep
B. keeps
C. keeping
D. kept
() 6. A. with
B. when
C. for
D. as
() 7. A. stop
B. to stop
C. stops
D. stopped
() 8. A. clean
B. cleaned
C. cleaning
D. to clean
() 9. A. let
B. make
C. had better
D. tell
() 10. A. spend
B. take
C. pay
D. cost

1. B
2. D
3. B
4. C
5. A
6. D
7. B
8. A
9. D
10. B

1. 根据前文“Long ago, there were not so many people on the Earth. There are no cars. There were many trees”可知，很久以前，没有很多人和汽车，有很多树，所以地球是干净的，A脏的，B干净的，C干的，D湿的，所以选B。
2. 后来城市变得越来越大，A来，B转变，C去，D变得，grow有“变得”的意思，在这里符合语境，所以选D。
3. “we throw our rubbish anywhere”是“We are hurting the Earth”的时间状语，当我们到处扔垃圾时就是在伤害地球，A什么，B当……时，C怎样，D哪里，所以选B。
4. 根据语境，当我们砍树时就是在伤害地球，A种植，B使用，C砍倒，D燃烧，cut down trees表示砍树，所以选C。
5. help do sth.表示帮助做某事，树帮助保持土地和空气清洁，所以选A。
6. as many...as...表示和……一样多，现在我们没有以前那么多的树了，所以选D。
7. 这里用不定式表目的，我们可以做很多事来阻止伤害地球，所以选B。
8. keep sth. + 形容词，表示使某物保持某种状态，我们可以种更多树来保持空气清洁，所以选A。
9. 我们可以竖立标志来告诉人们保持地球清洁，A让，B使，C最好，D告诉，tell sb. to do sth.表示告诉某人做某事，所以选D。
10. It takes some time to do sth.表示做某事花费多长时间，清理我们的地球可能需要很长时间，所以选B。