in order to do 什么時(shí)候省略in order

In order to do something 是為了春鬧去做某滾州事
She started taking weekend classes in order to learn how to cook.
為了學(xué)做料理他開(kāi)始在周末上課
to do 只是一般動(dòng)詞原形，像是 to go(去)， to read(閱讀)， to jog(慢跑)等都是動(dòng)詞原形。
It is difficult to do this math exercise.

寫這扒備罩道數(shù)學(xué)題很困難。