有人问： 请看下面两个句子：

(1)My teacher was preparing his lessons when I knocked at the door.

(2)My teacher was preparing lessons when I knocked at the door.

我认为第一句是正确的，而第二句是错误的，正如只可说：

(3)I finished my homework and then went out to play.

而不可说I finished homework...一样。但有人持不同意见，不知您的意见如何？

我们认为上述例（1）与例（2）都是正确的，其意义亦无甚区别，只是前者强调具体人即“他的”lessons, 后者则是泛泛而谈，不强调其特殊性罢了。这种在名词前或用物主代词或用零冠词（即不用冠词）的两可情况在英语里并不罕见，再如：

(4)John is doing （his）lessons now.

(5)Mary is arranging （her）books in order in her room.

(6)I saw a neat little old woman with （her）cheeks like apples.

不仅复形名词如此，单形名词亦可这样用，如：

(7)Have you had （your）breakfast?

(8)He liked （his）ease, and in his studio were a couple of heavily upholstered armchairs and a large divan.

(9)I like everything in （its）place.

(10)One of the carvings was of a mindless man with （his）mouth agape, his two arms protruding out of the side.

但有三点值得注意：

1. 在上述情况下，用零冠词时要注意英语习惯，绝不可随意杜撰。即以lessons为例，可以说prepare lessons或do lessons, 因为它们已变成了习语，但不可说finish lessons或neglect lessons，而应该说finish one's lessons或neglect one's lessons。

2.“零冠词+名词”结构并不都可以与“物主代词+名词”结构互换。如set eyes on不可变为set one's eyes on，反之，never take one's eyes off中的物主代词one's也不可省去。

3. 例（10）中的“零冠词+单形可数名词mouth”表示泛指，具有一种典型意义。但有不少情况则须用物主代词，如下面的句子绝不可省去物主代词：

(11)I have lost my book.

(12)The man wore his hat on one side.

最后，让我们回到你所举的例子。是的，只可说finish one's homework，不可说finish homework, 但可说finish school。为什么？ 一句话，习惯使然!