It is high time that the boy ______ sent to school.

问题描述:

It is high time that the boy ______ sent to school.
选项:
a、is
b、 was
c、 be
d、 is to be
选哪个?为什么?请分析并翻译整句

b.It is high time 后从句一定是过去时
到了孩子被送往学校的时间了