在《定冠词省不得》一文里，谈到了 5 个必须用定冠词的例子。

定冠词也出现在其他 11 种情况中，非同时注意不可。

⑴用在单数名词前面，以代表同类的人或物，如：

● The ox is a useful animal for farmers.

● This type of work is easier for the teacher than for the student.

但当涉及 man 和 woman 这两个名词时，一般上不必用 the ：

● Man is mortal.

● Woman differs from man in many ways.

⑵用在单数名词前面来表示有关名词的抽象概念，如：

● Don’t play the fool.

● Peter is fond of the bottle.

⑶用在数目字前面，如：

● Mr Li is somewhere in the 30s.

● She was not yet born in the 50s.

⑷用在测量单位前面，以表示“每”(each/per)，如：

● Some factory workers are paid by the hour.

● This car usually does 15 kilometres to the litre.

⑸用在比较级形容词或副词之前，以加强其意义，如：

● The teacher explained the idea again, but his students were none the wiser.

● Your mind will function all the better if you have some time away from your work.

⑹用在“the more/better……the more/better……”结构里，如：

● The more we practise, the more we improve.

● The better the staff, the better the performance.

⑺用在乐器名称之前，如：

● The piano sounds better than the organ.

⑻用在剧院、电影院之前，如：

● Do you often go to the cinema?

● Tom went to the Lido last week.

⑼用在四个方向之前，如：

● The sun rises in the east and sets in the west.

⑽用在复数姓氏之前，以表示有关家人，如：

● The Browns will visit us tonight.

⑾用在某些惯用语之前，如：

● We know the ins and outs of the matter.

● Compare the pros and cons before you make your decision.