was后面加原型还是过去式

was后不接原形，也不接过去式，was后面可接以下三种形式。

1、接现在分词表示过去进行时，比如“I was doing homework at this time yesterday.”意思即“我昨天的这个时间正在写作业”;

2、接过去分词构成被动语态，比如“He was scolded by his mother.”意思即“他昨天被他妈妈骂了”;

3、接动词不定式表示过去将来时，比如“He was to go to bed when his mother came home yesterday.”意思即“昨天他妈妈就回家的时候他正准备睡觉”。