空格 we were in beijinglibrary that day; a :it happened that; b:it was happened that如果b改成it was happening that;

问题描述:

空格 we were in beijinglibrary that day; a :it happened that; b:it was happened that
如果b改成it was happening that;

:it happened that是常用表达,一般不用it was happening that

it happened that 从句(碰巧.)是一个固定句型,这个句型中主句不用进行时.
但可以说sth is happening(发生)