1 翻译篱笆是由用过的易拉罐做成的

1,The fence is made out of second-hand(二手的)或者used soda cans.
made out of就是有什么做成的,用过的就是used,也可以用二手的代替.要看你有没有学到这个词了.
2,There used to be many manatees in the World.
The pollution of China is more than that in Canada.
第一句used to be是固定搭配,因为你讲的是过去式.
第二句在一个国家里用in,不是of.
3,Can you believe that in such a rih country there should be so many poor people.
选C,前面是讲这个国家有多有钱,形容程度应该用such,后面是数量,所以用so.
4,Mr Smith used to be a super surfer.But now he is too old to go surfing.
used to be就是曾经是,符合上下文.