1 做介词，表示“到，向，往”，如go to，fly to，后面跟名词作定语，构成介宾结构。
2 动词不定式的标志，很常见的，如：want to do，be happy to do。
扩展资料
一：表示相对，针对
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：表示对比，比较
1：以-ior结尾的形容词，后接介词to表示比较，如：superior ,inferior,prior,senior,junior
The quarrel happened prior to my arrival.
2: 一些本身就含有比较或比拟意思的形容词，如equal，similar，equivalent，analogous
A is similar to B in many ways.
3：表示一些先后顺序的形容词，如：second,subsequent,next,preliminary,preparatory
Subsequent to the war,they returned to their hometown.
4: to也偶尔出现在个别动词之后,与动词形成固定词组,表示比较,如:prefer to,compare to,incontrast to
compare to sth.表示比喻或比拟,而compare with sth.表示比较,如:
World is usually compared to a stage
Compared with his past,he has changed a lot.
Prefer的正确句型是:prefer A to B或prefer doing A to doing B,但当prefer后接动词不定式时,表示比较的介
词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与及个别的名词构成比较之意,如:alternative
Going to an under water concert is a great alternative to going to dinner.