【问】请问an amount of, a number of和a quantity of之间的用法有何不同? 下面三个句子表述得都正确吗?
1. A large amount of chickens were infected with the H5N1 strain of the bird flu.
2. A large number of chickens were infected with the H5N1 strain of the bird flu.
3. A large quantity of chickens were infected with the H5N1 strain of the bird flu.
【答】 上面三句只有第2句讲得通，第1句和第3句都是错误的。请看下面的说明：
an amount of通常与不可数、无生命的名词连用。如：
She spent a very large amount of money yesterday. 她昨天花了好大一笔钱。
a number of与可数、有生命或无生命的名词连用。如：
The president has made a large number of mistakes. 总统已犯了许多错误。
a quantity of通常与可数或不可数、无生命的名词连用。如：
A vast / large quantity of imported beer has been sold. 已经售出了大量的进口啤酒。
再者，从上面的例句可知，amount, number和quantity的前面经常使用vast, large, small 等表示数量大小的形容词来修饰，而这些形容词前面有时还会使用very等程度副词来修饰。不过，要特别注意的是，在这些用法中，large不可用big 来替代。