Progressive comparison是指[short adjective + er and short adjective + er | more andmore + long adjective ] 当你要描述程度上的增加或者减少的时候，可以用这个结构。

比如这两个句子:As the illness progressed, the patients grew more and more detached from reality. Marching into the sunset, the figures became smaller and smaller.

Combined comparison: [The short adjective-er/more+ long adjective + Subject 1(+to be), The short adjective-er/more+ long adjective + Subject 1 (+to be)] 这个结构用在我们想要表达一个事物怎么样，另一个事物也怎么样的时候。看下面两个句子：

The longer you leave it, the worse it'll get.

The more sophisticated the product, the more substantial the potential profit.

当我们对比两个相对的感情色彩时，我们可以用more而不是形容词的比较级。比如：

 I am more sad than disappointed. 比 I am sadder than disappointed.要更高级一些。

再比如：Hereyes are more green than gray.

当表达否定意义的时候，我们建议用not so much...as 或者rather than，比如：

I am not so much disappointed as sad.

Hereyes are green rather than gray.

当描述一个事物通过与其他有相似特征的事物对比时，我们可以用以下两个形式：

1）as+ adjective + as

例句：Listening to her was about as interesting as watching paint dry.

不过在口语里，我们有时会省略第一个as，像She looks white as a sheet.

2）like+ noun /verb phrase

看例句：

The cruise ship was like a skyscraper lying on its side.

There are many idioms in which we use these two patterns:

You are as white as a sheet I think you 'd better see a doctor.

I feel full of energy today -I slept like a dog last night.

需要注意的是：当我们描述两事物有相似点，同时又在名词前面时，我们会使用like而不是not as,比如：

 You look as a man who's seen a ghost!这个是不恰当的表达，正确应该是：You look like a man who's seen a ghost！

或者如：When Mike puts on his dark suit he looks like a waiter (= He resembles a waiter.)

但是当我们描述某人工作，地位，身份或者某物的功能时，在名词前用as而不是not like.

比如： Rachel's working like a waiter during the summer vacation的正确表达应该是Rachel's working as a waiter during the summer vacation. (This is her job.)