请问一个GWD语法题

coolerbb

Q3:

Not one of the potential investors is expected to make an offer to buy First Interstate Bank until a merger agreement is signed that includes a provision for penalties if the deal were not to be concluded.

 

1. is expected to make an offer to buy First Interstate Bank until a merger agreement is signed that includes a provision for penalties if the deal were
2. is expected to make an offer for buying First Interstate Bank until they sign a merger agreement including a provision for penalties if the deal was
3. is expected to make an offer to buy First Interstate Bank until a merger agreement be signed by them with a provision for penalties if the deal were
4. are expected to make an offer for buying First Interstate Bank until it signs a merger agreement with a provision for penalties included if the deal was
5. are expected to be making an offer to buy First Interstate Bank until they sign a merger agreement including a provision for penalties if the deal were

   Answer: c

为什么会deal后面用was呢？还有，为什么until a merger agreement be signed

wei_wangyan

请LZ到语法专区询问。