There are many kinds of fishes in the lake.
湖里有各种各样的鱼。
5. However, when he returned some years later, the colourful coral reefs were dead and grey.
然而，多年以后，当他回来时，艳丽多彩的珊瑚礁已经死了，变成灰色的了。
however conj. 然而；可是；不过；但是
Certainly he agreed. However, I won’t agree,
他当然同意了，然而我不同意。
注：however与but的区别在于，前者较为正式，but不能置于句首，而however 可以置于句首，句中或句末。置于句中时，前后用分号隔开的情况较多。
6. Since water covers most of the earth, Corsteau knew we should keep the seas clean.
由于水覆盖了地球的大部分，库斯托知道我们应该保持海洋清洁。
（1）since与because的区别在于，since常用于指众所周知的原因，而Because常用来回答Why的提问。
Since we are young, we should do more for our country.
既然我们年轻，我们应当多为国家做事。
— Why is Kate absent? 凯特为什么迟到了？
— Because she is ill. 因为她病了。
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since的另外一种用法，是表示“自从……以来”。
Where have you been since I last saw you?
上次我和你见面以后，你到哪里去了？
It is a week since we arrived here.
我们到这里来已经有一个礼拜了。
（2）本句中cover的用法，意思是“用……遮盖；覆盖”。
Snow covered the ground.
雪覆盖了地面。
She cried and covered her face with her hands.
她哭了，用手蒙住了脸。
The desk was covered with dust.= Dust covered the desk.
书桌上布满了灰尘。
7． …, he encouraged everyone to take part in protecting our lakes, rivers, seas and oceans.
……，他鼓励每个人加入到保护我们的河流、湖泊和海洋的行动中来，take part in意为“参加（活动）”一般表示在活动中还承担一定的职责。
He always takes an active part in all kinds of activities in school.他总是积极参加学校的各种活动。
join也有参加的意思，但是该词主要强调参加某项组织。如：He joined the party when he was eighteen years old.他十八岁就入了党。
上学期 Unit 6 Mainly revision由www.yf1234.com收集及整理,转载请说明出处www.yf1234.com
上学期 Unit 6 Mainly revision