请教GWD6-14

Q14:

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

选A.

deal后为什么是"were" 不是"was"?  这里是虚拟吗?  为什么用虚拟?  谢谢!!

-Lucy

我也选了C

NN可以讲讲吗，不是说虚拟主句要原型吗