单选题 ______ for your help, we'd never have been able to get over the difficulties.
   A) Had it not                           B) Had it not been
   C) If it were not                       D) If we had not been
【正确答案】 B
【答案解析】非真实条件if从句中如果含有助动词should，could，had，或were可以倒装并同时省略连词if。