前三句都是考察否定词前置时,谓语动词的倒装问题.
1.正常语序为：It did not stop raining until yesterday afternoon.以Not until 开头时,助动词did 要提到主语it 之前,句子变为：Not until yesterday afternoon did it stop raining.
2.正常语序为：He not only made a promise but also kept it.以Not until 开头时,不是谓语动词made直接提前,而是将助动词did 放在主语he 之前,实体动词（原型）make 仍在主语后面,句子变为：Not only did he make a promise but also (he应该省略) kept it.
3.道理是一样的,你可以自己分析一下.
4.原句是：I have many friends ,some of them(指代many friends) are bussinessmen.后一句变为定语从句来修饰many friends,修饰人的定语从句用who,whom引导,这句形式为of whom(不能用who,of 后面要跟宾格,如要说some of us,而不能说some of we) .
5.从后面的句子意思可以分析出,问句是问200块够吗?完整的句子是Will ￥200 be enough?用省略句的话,就用do代替be enough