B
be made of是指看的见的材料做成的.如：Books are made of paper.
而be made from是指看不见的材料制成的.如：paper is made from mood.
本题桥是铁做的.我们能看见铁,所以用be made of
多看几个例子你就知道了
The doors of the palace were made of beaten gold.
宫殿的门由金箔做成.
2. Light often behaves as if it were made of particles.
光常常表现出好象它是由粒子组成似的.
3. The fence was made of posts joined together with wire.
篱笆是以铁丝连接起木桩而构成的.
4. People used to test coins that were offered in payment, to see if they rang true or were made of false metal.
过去人们在收到付款时,常常试扔一下硬币,听听其声音是真的,还是由假金属制作的.
The coat was made from lambskin.
那件衣服是用羊皮做的.
2. A fine yarn made from the wool of sheep raised in the Shetland Islands and used for knitting and weaving.
设得兰毛线系由在设得兰群岛饲养的羊的羊毛制成的精制毛线,用于针织和编织衣物
3. Wine is made from grapes.
葡萄酒是用葡萄酿成的.
4. A container, such as a powder horn, made from a horn.
角制容器一种由动物的角制成的容器,例如装枪药的角制容器
5. These pancakes are made from batter.
这些薄煎饼是用牛奶、鸡蛋、面粉调成的面糊做的.
6. Pyjamas made from flammable material have been removed from most shops.
大部分商店都不再出售用易燃材料做的睡衣了.
7. The dish was made from the entrails of a sheep.
这盘菜是羊杂碎.