Model :
a) He left the University two hours ago.
He left the University two hours ago, didn’t he? —Oh yes, he did .
b) He did not leave the University two hours ago.
He did not leave the University two hours ago, did he? — Oh no, he didn’t.
1. a) My niece studied English in the Language Laboratory yesterday .
b) My niece didn’t study English in the Language Laboratory yesterday.