有律師問律師，別人不知詳情不好建議

To have a contract or agreement, both sides have to agree.

One side propose an agreement to the other side, this is simply an "offer".

An offer has to be accepted to become "contract" or "agreement".

Anybody who bought a house would unerstand this.

In this case, I see an Offer, but I don't know if there was acceptance.  If there was, then this could be an agreement.  If there weren't acceptance, this is simply an expired (or standing) offer. 

An acceptance has to be "yes, I agree all".  A reply of "yes, but here is what I wanted" is simply an counter-offer.

Again, anyone who bought a house would understand this.