问6道高中英语单选题,请写出解析

问6道高中英语单选题,请写出解析
1 Many a passenger ___ complaining the delay of the flight,for the majority of them are businessmen who are short of time.A is B are
2 Goods are __ as long as they are in good condition.Aexchangeable Bexchanged
3 I,who ____ your teacher,will try my best to help you with your study.Aam Bis
4____ the climate changes so much has caused many discussions among the scientists.AWhich BThat
5____ he talked about it to reporters surprised me.AWhich BThat
6____ we can raise our production remains a problem.AWhich BHow
这些高中英语单选题为什么 正确答案都选A,请写出所选答案的理由
书上写了应该选A正确答案怎么不是B，求原因.