单复数用法答疑

GWD:

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.

A.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.

B .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 not to be concluded.

C..is expected to make an offer to buyFirst Interstate Bank until  a merger agreement be signed by them with  a provision for penalties if the deal were not to be concluded.

D.are expected to make an offer for buying First Interstate Bank until it signs a merger agreement iwith a provision for penalties if the deal was not to be concluded.

E.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 not to be concluded

选择C.

我的疑问是：

1.not one of +名词复数，后面谓语到底该是单数还是复数。在《语法全解》里，no +名词，由名词决定单数复数。那这种情况呢？

2.C使用BE signed 为什么是be signed

3.include 和with 功能是不是一样的。如果用including a provision for penalties if the deal was not to be concluded.可以吗

4.C 选项用the deal were not to be concluded 为什么是were?

谢谢nn们的指点。