Quote Originally Posted by Faisal Marri View Post
We don't need change/correct the whole phrase. If we do, we get no marks. The sentence has one grammatical error and we need find that error and correct it.
Seriously? Let's look at sentence two (the first one in my post), thus:

After graduation, my father wants me to join his business firm.

That makes it seem like "my father" is the one who is graduating. Instead, you want to make clear that "my father" wants me to join the firm (company) after "I" graduate.

Always strive for clarity.