isn't high time _ responsibly,with our nation's future in mi

It is (high) time that后面的从句谓语动词要用过去式或用should加动词原形,但should不可省略.
It is time that the children went to bed.
It is high time that the children should go to bed.
it's high time that sb.did sth.
多用在虚拟语气中,是时候某人该做某事了,并不表示过去时态
表示“是该做.得时候了”

high time 的用法和wish的用法是相同的 你看看 wish后面跟的形式 对比一下就明白了
should一般是用在过去时或者表达一种询问或者希望的语气的句子中

It is (high) time that后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
It is time that the children went to bed.
It is high time that the children should go to bed.
it's high time that sb. did sth.
多用在虚拟语气中,是时候某人该做某事了,