This camera is too expensive. I'd like a ______ one.

A. cheap   B. cheaper    C. cheapest   D. more expensive

The road is too narrow, and we are going to build a ______ one.（wide, wider）

▲我认为，以上两句都应该使用比较级，分别为：cheaper 和wider。

原因是，前一(分)句分别给出了一个可比较的camera 和road，涉及两个同类对象，这时须用比较级。a cheaper one 说明比刚才提到的那个便宜。

这两个句子，实际省去了比较的成分，现在添加上就好理解了：

This camera is too expensive. I'd like a cheaper one (than this camera).

The road is too narrow, and we are going to build a wider one (than that road).

 ▲仔细体味下面的句子，为何用比较级？不用的话，能否准确表达出想要表达的意思？这些句子同样可以添加上被省略的比较成分。

That is too expensive. Can you show me something cheaper?

That one is cheaper, but I do prefer this one.

Jane was always bullied by the bigger girls.

We are living in a very small house. I am hoping for a bigger one.

Stand back to back and let's see who's taller.

Seen from within, the cave looked larger.

It's easy to be wiser after the event.