1.essential adj.极其重要的，必不可少的 n．必需品，必不可少的东西
(教材原句)Which sentences contain a clause with essential information and which with extra information？哪些句子包含一个含有重要信息的从句，哪些句子包含一个含有附加信息的从句？
?It is essential that you (should) come home early.
你有必要早点儿回家。
?It is essential for us to know all the facts.
对我们来说，了解所有的事实是必要的。
?Because I live in a remote village, I regard my car as an essential.
因为我住在一个偏远的村子里，所以我把汽车看作是必需品。
