20(时间、条件和让步状语 )

如主句用将来时，在时间、条件和让步状语从句中要用一般现在时表示将来。又因if 从句是take notice of...的被动语态结构，故选A。 上面是一道题的答案，我想问如何分辨时间、条件和让步状语 请从如下方面解答： 1：亘古不变，用规律可循的 （如固定的单词......）一定要全啊谢谢 2：灵活变通的 ......

解题思路： 时间、条件和让步状语
解题过程：
1.时间状语从句:表示时间性质的状语从句
例句：It's five years since he smoked他吸烟已经有5年了(since he smoked是时间状语从句)
引导词有：when,as,while,before,after,since,till/until,as soon as,once,whenever,so(as)long as,by the time,each time,every time,immediately等。另外还有：hardly...when,no sooner...than
2.条件状语从句：表示条件或要求性质的状语从句
例句：
1）I can lend you the bike on condition that you return it on time我可以把自行车借给你，但条件是你必须限期归还(on condition that you return it on time是条件状语从句)
2）You'll fail if you don't work hard如果你不努力就会失败(if you don't work hard是条件状语从句)
引导词有：if,unless,so(as)long as,on condition that(只要）等。
3.让步状语从句表示：虽然，尽管，即使等概念，由although（尽管）, though（尽管）, however（无论怎样）, whatever（无论什么）, whoever（无论谁）, whomever（无论谁）, whichever（无论哪个）, whenever（无论何时）, wherever（无论哪里）, whether（是否）, no matter (who, what, where, when, etc) （无论……）, even if（即使）, even though（即使）等词引导。
如： We won”t be discouraged even if(=even though) we fail ten times.我们就是失败十次也不泄气。
It was an exciting game, though / although no goals were scored.那是一场精彩的球赛，尽管一个球都没进。(though, although不能与 but连用)
让步状语从句表示：虽然，尽管，即使等概念，由although（尽管）, though（尽管）, however（无论怎样）, whatever（无论什么）, whoever（无论谁）, whomever（无论谁）, whichever（无论哪个）, whenever（无论何时）, wherever（无论哪里）, whether（是否）, no matter (who, what, where, when, etc) （无论……）, even if（即使）, even though（即使）等词引导。
如： We won”t be discouraged even if(=even though) we fail ten times.我们就是失败十次也不泄气。
It was an exciting game, though / although no goals were scored.那是一场精彩的球赛，尽管一个球都没进。(though, although不能与 but连用)
Whether you believe it or not, it”s true.不管你信不信，这是真的。
However (=No matter how) expensive it may be, I”ll take it.无论它有多贵，我也要买下它。
Don”t let them in, whoever(=no matter who) they are.不管他们是谁，别让他们进来。
No matter what I say or how I say it, he always thinks I”m wrong.无论我说什么或怎么说，他总认为是我错。
特别提醒
1.no matter
what（who，which，when，etc。）与whatever（whoever，whichever，whenever，etc。）的区别：
当引导让步状语从句时，两者相同，可以互换，但当引导名词性从句（主语从句，宾语从句，表语从句和同谓语从句）时则只能用whatever（whoever，whichever，whenever，etc）。如上面最后两个例句可改为：
e．g． However pure the water looks，I do not want to drink it。
I want to marry the man I love， no matter who he may be。
下面句字不能用no matter结构:
Whoever comes back firs is supposed to win the prize.(主语从句)
I am ready to do whatever you want me to .（宾语从句）
2. as 引导让步状语从句的用法：
引导让步状语从句时，as意为“虽然，尽管”，通常从句要倒装，倒装的方法是将从句的表语或状语放在as之前，而用though引导让步状语从句时句字则不必倒装（口语中也可倒装）。
e.g. Heavily as it was raining outside, they started out very early.
Young as he is, he knows a lot=Though he is young 或Young though he is, he….
他虽然年轻，但懂得很多。(though 也有这种用法，可以替换as,但although没有这种用法)
though还可以用作副词，放在句末。如：
It was hard work;; I enjoyed it, though=It was hard work, but I enjoyed it.那工作很苦，但是我喜欢干。
3.用though/although, as 引导让步状语从句时，句中不能用but表示转折语气。
不能说：Though he looks weak, but he is healthy.
而要说：Though he looks weak, he is healthy.
或者说：He looks weak, but he is healthy.
这里要指出一点，状语从句有一点要注意，就是当主句是将来时，从句要用一般现在时

最终答案：略