he traveled to many mountain villages and saw many poor children out of school .this experience ____________his life.
A.would change B.had change C.was to change D. was change...A和C搞不明白，求解答

after a while an agreement __,
A.was arrived at B.was arrived in C.arrives D.is going to arrive .
为什么要加介词？答案是a

she was ______by us
A.is elected leader b.was leader elected c.was elected leader d.leader was elected,答案是c，为什么不是b呢？不是分词短语要作后置定语吗

秒沉，，，妹的

第一题

第二题

第三题 leader是was elected的补足语

再来几题，表示高中生压力大啊

i tried to phone her ,but evenas i______she was leaving the building.
a.phoned b.would phone c.had phoned d.was phoning
答案是d来分析分析

-was andrew there when you arrived?
-yes,but he ______home soon afterwards.
a.had gone b.has gone c.is going d.went ,答案是a，我很怀疑答案的正确性..

-well,that was really a good meal.i _____you were a really good cook.
a.did not know b.dont know c.have not known d.had not known，好吧，其实我是搞不清楚完成时和过去式的区别，语法书上说的太抽象，说啥现在完成时侧重对现在的影响，我表示不理解，答案是a，求大神分析分析a和b的区别，纠结完成时和过去式很久了，，..