你的理解是对的：①insisted 后面的 that 引导的是宾语从句；②worth paying attention to 为 the key word 的修饰语；③should be underlined (被动语态)不是修饰从the key 到 to的全部，它是主语the key word 的谓语部分。④由于 insist（表示“坚持要”）后面接 that 从句时，通常用“should+动词原形”（其中的should可以省略），即原句相当于：Our teacher insisted that the key word worth paying attention to (should) be underlined before class.又如：The detective insisted that he (should)have a look. 警探坚持要查看。I insisted that he (should)go with us. 我坚持要他和我们一块儿去。 【