GWD6-14是虚拟语气吗？

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

   Answer: A

我选的是B。A和B比较，只有最后那个if the deal were, if the deal was的不同。答案选A，是不是因为是虚拟语气呀？如果是的话，怎么辨别用if后面应该用虚拟还是不虚拟呀？谢谢

是虚拟语气。

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.

以上情况是虚拟语气，具体说叫＂推测条件句＂中的虚拟．

虚拟语气：把动作当作一种只存在于讲话人想象中的＂假设＂或者＂推测＂，而不是当作客观现实中的真实事件．

推测条件句的结构：

１、if subject +动词过去式

２、if subject +should +动词原形

３、if subject  +were to do

本句属于３

if本来就是表示“如果”，那是不是IF后面都虚拟呢，谢谢

请问 one of + 名词复数 who/that + V 复数

这里是否因为 one of 名词复数没有（who/that）所以是单数呢