It is (high / about) time that.问：is可以 用was吗?It "was" (high / about) time that 请大师详解

这个无所谓吧，只要后面是should do 和 did 就行了好像

It's time + that clause 时，that可

1、虚拟语气用于“条件虚拟句”、“so that 和 in order that 引导的目的状语从句（谓语动词前用情态动词 can/could 或 may/migh）” 以及表示 “个人态度的名词从句”.
2、It is time that 就是表示个人态度的名词从句,含义是 “我认为早就该或本该做某事了,但是却没有做”.该句型中that 引导的是主语从句,从句中要求用与事实相反的虚拟语气.对现在虚拟用过去时（be 一般用 were）,对过去虚拟用过去完成时.如：
　　It is time that you got up. 你早就该起床了.（表明对现在“你”迟迟不起床的态度）
　　It was time that he had set out on time. 他当时本该按时出发的.（表明“他”在过去没有按时出发的态度）
3、time 可以用 high, due,right 等形容词修饰,强调 “正是该做的时候”,或者用介词短语about time 强调 “差不多该做的时候”.
4、类似的这种特殊名词从句有跟在 wish、had better、would rather 后的宾语从句,如：
　　I wish that you were with us.（但愿你和我们在一起/要是你和我们在一起就好了）
　　You had better that went out for a walk. （你要是出去散步该有多好）
　　We would rather that he had stayed at home yesterday. （我们宁肯他昨天呆在家里 ,那该多好）

It was (high)time that从句中使用had done
It was (high)time that we had set out
It is (high)time that从句中使用一般过去式
It is (high)time that we set out
因此，不能简单的替换。