Tell him about this site and send him emails in English.

The college entrance examination is different from the actual language competence. It takes more skills to take it. I would suggest him do some real exercises and anylise why he did not do it right. Is it because he is not familiar with certain grammars , or he understand the meaning the other way (in reading comprehension)? Practice makes perfect. It's very important to rethink and reflect on his own paper.

He needs to do some past exam papers for revision, so he knows what to expect. You can't force people to like English. A lot of boys will say a subject is 'boring' because they find it difficult and they say this in order to 'save face'. Either he needs to pass this subject or not.

You can't. Let him get on with it himself.

Did you already try with one of the followings: a) English songs with lyrics ? b) English movies with subtitles ? c) How about showing him that (at least in scientific subjects) most of the books are published in English language and (occasionally) translated, the same holds for scientific magazines ? d) Tell this young man that the miniskirt has been invented in England . (I ignore whether a Nobel prize followed or not)