虚拟语气、except的题1.I____writing the article by the time you get

虚拟语气、except的题
1.I____writing the article by the time you get back.A shall finish B must have finishedC have finished D.shall have finished答案是D B为什么错了？2.The voter told the politician that he could___ on their support in the next general elections,A.expect B decide C.count D.doubt答案是C 有expect on 这个词组吗？ 其他选项是说只有count 和on才可以组成词组其他都不成吗3.He never wrote to his father____he was in need of money.A.except B except when C. except for D.except that答案是B 请讲一下几个选项的用法 谢谢～