لماذا يعتبر هذا هو الحل الصحيح

[مستر طارق فؤاد]

It really pleases me that you have this discussion.


Let me take you to another one that I had with a colleage:

I set the following sentence on the monthly school test:
He took a taxi. It was not necessary to do so. (Use : have)

Will you use: didn't have to , needn't have, or both are right?
I'm waiting for you opinions