It is high time that someone()you how to behave yourselfa,taught b,teaches c,shall teach d,will teach为什么选a

It is high time that someone()you how to behave yourselfa,taught b,teaches c,shall teach d,will teach为什么选a
It is high time that someone()you how to behave yourself
a,taught b,teaches c,shall teach d,will teach为什么选a

It is high time that someone()you how to behave yourselfa,taught b,teaches c,shall teach d,will teach为什么选a
亲,这是虚拟语气的固定用法.
It is high time that...后面接过去式,表示是该发生什么什么的时候了.

it is time that 从句中的谓语动词习惯用过去时，表示这个时候你该做这事但你还没有去做，类似虚拟语气。所以用A。

It is high time that ……是虚拟语气的一种短语。

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。
语法规则喽