英文咁寫可以嗎?

No,it is wrong.
________________
If I were you....................

I go to library in order to prepare the English Exam
I go to library because I am preparing the English Exam

2010-12-20 17:50:15 補充：
To 001,
I go to the library for studying the coming examination

It will be better

2010-12-20 17:51:54 補充：
To 002,
As I prepare for the examination, I go to library for studying

發問者 : I go to the public library to revise for the coming exam./I go to the public library to do revision for the coming exam.

present tense: I am now going to the library to prepare for my examinations.
Past tense: I went to the library to prepare for my examination.
You can not use 'in' for preparation. you should use prepare instead of preparation and to library isn't very good you should use to the because library is a noun (名詞)

I go to the Students' Study Room in the library to prepare my exam.

In order to prepare my coming examinations I go to the library .

to prepare for the examination, i will go to library to study

I go to the library to study for the examination coming soon.