to cut down air pollution, we should take the bus or subway instead of driving. 为了减少空气污染，我们应该乘坐公共汽车或者地铁，而不是开车。to cut down air pollution是动词不定式作目的状语。往往译成“为了…”。 这种用法很常见。如： To catch the first bus, he got up early. 为了赶上头班车，他一大早就起来了。
It's good for health and it doesn't cost anything! 它对健康有益而且不用花钱。 “be good for” 对…有益，对…有好处。cost花费。它是一个用事物作主语的动词，其他词如：pay, spend则要求用人做主语。
And remember to throw rubbish in the cans 还要记得把垃圾扔进垃圾桶。 “remember to do”是记着作…” “remember doing”是记的做过…” 如： Please remember to turn off the light when you leave. 请记着离开时把等关了。（现在灯还没关） I remember turning off the light. 我记得我吧灯关了。（灯已关） 。
our actions can make a difference and lead to a better future! 我们的行动能影响他人，创造一个更美好的未来! “make a difference” 是“有影响， 有作用”。
Sharks are at the top of the food chain in the ocean's ecosystem. 鲨鱼处于海洋生态系统食物链的顶端。 “food chain”: 食物链。 He now owns a chain of 970 food stores. 他现在拥有970家连锁食品店。
Have you ever thought about how these things can actually be put to good use? 你是否曾经想过这些东西还能很好地重新利用? “put… to good use”: 充分…利用，
she is a most unusual woman. 但她是一个非常不寻常的女性。most前用a时，most = very.
The top of the house is an old boat turned upside down. 房子的顶部是一条翻转过来的旧木船。“turned upside down”这是一个过去分词短语作后置定语。意思是 “被翻转过来的”
And the gate in front of her house is made of rocks and old glass bottles. 房子前的大门是用岩石和旧玻璃瓶搭建的。 “be made of”: 用…材料做的。注意和be made from的区别。一个产品，如仍能看得出其原材料，就用be made of，如已看不出其原材料，就用be made from。如： The desk is made of wood. 课桌是用木头做的。(仍能看出其原料)。 The wine is made from grape. 这酒是用葡萄做的。(已看不出其原料)。
“Amy is an inspiration to us all.” 艾米给了我们所有人一个启示! “be an inspiration to”: 对…是个启事。类似的还有：“be an example to”: 为…树立了个榜样。
Amy isn't the only one who is good at recycling. 艾米不是唯一一个擅于废物利用的人。定语从句的先行词前如有the only, 从句中的谓语动词要用单数形式。如： She is one of the students who speak French. 她是讲法语的学生之一。She is the only one of the students who speaks French. 她是学生中唯一讲法语的学生。
“I plan to write a book about new ways to use old clothes,” 我计划写一本关于用新方法来改造旧衣服的书。 “to use old clothes” 是动词不定式作定语。修饰ways。Way常用不定式来修饰。如：I have found a way to solve the problem. 我已找到解决这个问题的方法。
重点句子归纳：
To cut down air pollution, we should take the bus or subway instead of driving.
It's good for health and it doesn't cost anything!
I think simple things like bringing a bag to go shopping can help.
If their numbers drop too low, it will bring danger to all ocean life.
Many believe that sharks can never be endangered because they are the strongest in their food chain.
So far, no scientific studies have shown that shark's fins are good for health,
以下这些动词后只能跟动名词：mind; enjoy; practise; stop, suggest; keep (on); advise; finish;
这些动词都是及物动词，如果它们的宾语是动词的话，必须用动名词形式，不能用不定式。
例如：
1. Would you mind opening the window?
2. He enjoys doing homework.
3. I practise speaking English in the morning.
4. Xiao Li kept asking questions in class.
5. I have finished writing my composition.
下列动词后跟不定式：
以下动词后只能接不定式：agree同意, 赞同, arrange安排, choose选定, 愿意, decide决定, 决意, determine决定, be determined决心, fail不, 不能, 忘记, learn学, 学会, manage。设法；wish愿望, 渴望, 等等。例如:
He pretended to be angry．他假装生气。
I promised to wait．我答应等着。
Do you wish to see the manager? 你想见经理吗?
课堂在线小测验
一、课文理解检测
have heard of shark's fin soup. This famous and expensive dish is especially in southern China. But do you realize that you're killing a whole shark you enjoy a bowl of shark's fin soup?
When people catch sharks, they their fins and throw the shark into the ocean. This method is cruel, harmful to the environment. a fin, a shark can swim and slowly dies. Sharks are of the food chain in the ocean's ecosystem. If their numbers drop low, it will bring to all ocean life.
参考答案：
Many, popular, each time, cut off, back, not only, but also, Without, no longer, at the top, too, danger.
课后阅读
I've got my gloves on
Mark Twain was a famous American writer and James Whistler was a famous American painter. They were good friends.
One day Twain visited Whistler in his house. He walked about looking at Whistler's paintings.
"I like this picture of the sea." Twain said.
"Yes, I painted it some time ago. It's called ‘The Angry Sea'.”
"The colors are beautiful.” Twain said. Then he pointed at another picture. "I like the way the woman is standing in this picture. I like the way she's looking out of the window."
"Thank you," Whistler said.
"What are you painting at the moment?" Twain asked.
"This," Whistler said and he showed Twain an unfinished picture. "This is going to be the best picture I've ever painted."
"Yes, it is," Twain said, “It's so beautiful that I want to feel it with my hand!” with this, he put out his hand to the picture.
"Stop that!” Whistler cried. “The paint isn't dry yet!”
"I know," Twain said, "but it's all right. I've got my gloves on.
