caution的形容詞形式怎么寫

　　例句：

　　Caution! This truck is reversing.

　　小心！卡車在倒車。

　　'Caution' is the key word in this situation.

　　在此情形之下，caution為關鍵詞。

　　I would caution against getting too involved.

　　我要提出警告，別介入得太深。