表示：“早該做某事了”時，定語從句中的謂語動詞須用虛擬語氣，其虛擬語氣的結構為：
It is (high / about) time that + 主語+ 動詞的過去式/ should + do（優先使用動詞過去式），即從句用虛擬過去式。
如：
It is time that I went to pick up my daughter at school. 我該去學校接我的女兒了。
=It is high time I should go to pick up my daughter at school.