no bus,we had to walk home.

There was

There being

Because there being

It being

考查独立主格结构。句意：没有车，我不得不走路回家。根据句意，表示“存在”，要用there be 句型；分析句子可知，设空处应用非谓语动词，there be只有主动形式，故用现在分词；因为非谓语动词有自己独立的的主语no bus,所以此处是独立主格结构。故选B项。

Last night I had just gone to bed          an odd delivery man knocked on the window of my house.

as

before

when

while

考查状语从句引导词。句意：昨天晚上，我刚刚上床睡觉突然觉得一个奇怪的送货员敲我房子的窗户。固定搭配had  done sth when表示某人刚做完某事突然.....故选C项。

We’ll make the final decision on our scheme. ______ you change your mind, please inform us as soon as possible.

Should

Were

Would

Had

考查虚拟语气的省略。句意：我们将对我们的计划做最后决定。如果你改变主意，请尽快通知我们。根据语境，此处用虚拟语气，表示与将来相反，从句用should+动词原形，省略if，should提前，陈述句是：If you should change your mind……。故选A。