1）介词后面的关系词不能省略。 2）that前不能有介词。 3） 某些在从句中充当时间，地点或原因状语的“介词+关系词“结构可以同关系副词when 和where
由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。As一般放在句首，which在句中。As we know, smoking is harmful to one's health.Th
1)Whoever spits in public will be punished here. (Whoever 可以用 anyone who 代替) 2)The parents will use what they have to send their son to technical school. (what 可以用all that代替)
1）what = the thing which；whatever = anything What you want has been sent here. Whatever you want makes no difference to me. 2) who= the person that whoever= anyone who （错）Who breaks
1）不用that的情况a) 在引导非限定性定语从句时。 (错) The tree, that is four hundred years old, is very famous here.b) 介词后不能用。 We depend on the land from which we
19.1 地点状语从句地点状语从句通常由where, wherever 引导。 Where I live there are plenty of trees.我住的地方树很多。Wherever I am I will be thinking of you. 不管我在
地点状语从句通常由where, wherever 引导。 Where I live there are plenty of trees.我住的地方树很多。Wherever I am I will be thinking of you. 不管我在哪里我都会想到你
方式状语从句通常由as, (just) as…so…, as if, as though引导。 1） as, (just) as…so…引导的方式状语从句通常位于主句后，但在(just) as…so…结构中位于句首
比较：because, since, as和for 1） because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，就用as或 since。
表示目的状语的从句可以由that, so that, in order that, lest, for fear that, in case等词引导，例如： You must speak louder so that /in order that you can be heard by all. He wrot