HI ! I have a question

Hello !

I received an the offer for of a Master Degree today.
And I am waiting for offers from others school's too. offer.

But, I don't want to reject this school,  so, should I ask for the "deadline to respondse"? 
Or should I accept the offer first, and then once i should I get another, better offer, then i reject the first offer?

HI ! I have a question

Hello !

I received an offer for Master Degree today.
And I am waiting for others school's offer.

But, I don't want to reject this school
should I ask for the "deadline to response"
Or
should I accept the offer first, once i get another better offer, then i reject the first offer?