prefer to（二词连在一起的话）,跟动词原形,to与动词原形构成动词不定式.例：
Russia and China have already said that they prefer to fight their own battles.
CNN:CLOSING IN ON CRIME
On these flights,travellers usually prefer to work,socialize or enjoy the in-flight meals and entertainment.
BBC:Getting your money’s worth in business class
Distracting lights you'd prefer to hide in a darkened room while gaming or watching a movie?
ENGADGET:PSP Go scores its first mod job,a handful of white LEDs find a new purpose in life
prefer.to.（二词分开时）,跟名词或动名词,to为介词.例：
prefer grapes to cucumbers 更喜欢葡萄而不是黄瓜
prefer dancing to singsing 比起唱歌更喜欢跳舞
