So it is important that you should think before you say or do anything.
=So it is important that you should think before you say or do anything.
上列句中的important為形容詞, 表『有必要的』, 此類表『有必要的』形容詞用於"It is + 此類形容詞 + that子句"之句構中時, that子句中須使用助動詞should, 但should常予以省略, 而直接接原形動詞。常見的此類形容詞計有下列數個:
+ that + 主詞 + (should) + 原形動詞
例: It is imperative that Carlos (should) get married before his girlfriend changes her mind.
It is essential that the nurses (should) learn to be patient.