It is (was)+形容詞（或過去分詞）+that…… 結構中, 常用的形容詞：

natural (自然的),appropriate (適當的),advisable (合適的),preferable (更可取的),

better (更好的)，necessary (必須的),important (重要的),imperative (急需的)

urgent (急迫的),essential (本質的),vital (必不可少的)，crucial（緊急的）

probable (很可能的),possible (可能的)，desirable (極好的)，advisable（合理的）,

compulsory（必須的）,desirable（理想的）, essential（必要的） ,

imperative（迫切的）,incredible（驚人的）,necessary（必要的）,

possible（可能的）,strange（奇怪的）,urgent（緊迫的）。。。

It is important that

It is believed that

It is interesting that

It is necessary that

It is suggested that

It is time that