Thanks MM for your answer. But it's not really helpful because it's not related to my question at all.(I hope I didn't sound rude but I felt very frustrated of not getting understanding at all.)
Please, here is my question:
我的问题主要是针对: 既然 "in order to与to可以互相替代使用,但是OG说过,to是in order to的省略形式,更间接,优先使用to来表目的", 为什么ETS 说C 要加"in order": The infinitive must be preceded by a conjunction (in order) ?