to可以是介詞，也可以是結構助詞。作介詞用的時候，后面跟名詞或動名詞，作結構助詞用的時候，是做不定式，后面必須跟動詞原形，等用法。下面小編整理to的各種用法。

一：表示相對，針對

be strange (common, new, familiar, peculiar, distinct, sensitive, immune, vulnerable, indispensable)to

Air is indispensable to life.

Aircrafts are vulnerable to interference caused by radiation.

This injection will make you immune to infection.

二：表示對比，比較

1：以-ior結尾的形容詞，后接介詞to表示比較，如：superior ,inferior,prior,senior,junior

The quarrel happened prior to my arrival.

2: 一些本身就含有比較或比擬意思的形容詞，如equal，similar，equivalent，analogous

A is similar to B in many ways.

3：表示一些先后順序的形容詞，如：second,subsequent,next,preliminary,preparatory

Subsequent to the war,they returned to their hometown.

4: to也偶爾出現在個別動詞之后,與動詞形成固定詞組,表示比較,如:prefer to,compare to, in contrast to;compare to sth.表示比喻或比擬,而compare with sth.表示比較,如:

World is usually compared to a stage

Compared with his past,he has changed a lot.

Prefer的正確句型是:prefer A to B或prefer doing A to doing B,但當prefer后接動詞不定式時,表示比較的介詞to就要改成rather than ,如:

The undaunted soldier preferred death to surrender.

Many people prefer spending money to earning money.

They prefer to pursue careers rather than remain home as house wives.

5: to與及個別的名詞構成比較之意,如:alternative

Going to an under water concert is a great alternative to going to dinner.

三: 表示修飾關系

1: 表示回復,反應意思的詞,如:answer to question,

solution to problem,response to inquiry,reaction to proposal,reply to letter

2: 表示建筑構件的詞匯,如: entry,entrance,approach,access,passage,exit,vent,path

the approach to a bridge引橋

the approach to science

Half of the population was estimated to have no access to the health service.

The access to education 接受教育的機會

The access to medical care 享受公費醫療的權利

3: 表示人物職位和官銜的詞,如:assistant to manager, ambassador to Spain, successor to

tradition, heir to throne, deputy to the National People\'s Congress;advisor to the Prime Minister

4: 表示權利和許可的詞匯,如:right,admission

The employee finally got the admission to the boardroom.

Everyone has an equal right to …………

5: 表示柵欄或障礙的詞匯,如:bars to development,the barrier to progress

6: 表示與書籍,文本相關的詞,如:introduction to passage.

7: 表示恭喜或是祝賀,如:

The director proposed a toast to the health of the guests.

Let\'s drink to Dick\'s success in business

8: 另外還有一些名詞符合這種用法,有的具有兩者息息相關,缺一不可的含義.如:key to door,invitation to party, guide

to action,limitation to life,accessory to school