 Re: what is the mistake?
[CAUTION: I am not a teacher:take the advice and or corrections offered in this post at your own risk.
If you doubt the information, please get a qualified opinion from one of the teachers on these forums.]
That looks right to me. In addition you might write out the incorrect and correct forms, or at least a corrected form of how the sentence should read.
If you are uncertain about instructions in the future, the best person to ask is probably the one giving you the assignment.
|