It was的缩写

It was和It has一般不缩写

It is在强调句中不缩写
It is you that called me.
在陈述句中可缩写
It's you!

it was不能缩写
底下两个都是it's
根据句子理解是那个词

不会混淆
it is -- it's
it has or it was 没有缩写