(4) 原因状语从句的引导词

连词	词义	例句
because	因为	Everyone likes my brother because he is friendly.
since	因为,既然	Since we have no idea about it, let's ask Mr. Li.
as	因为,由于	As it was getting late, I decided to start for home.

【经典例题19】(2019江苏无锡) ―The local food may taste a bit strange.
―Well, __________we are here, why not give it a try?
A. though              B. unless               C. since               D. because
【答案】C
【解析】考查时间状语从句。句意：——当地的食物可能有点怪。——既然我们在这里，为什么不尝尝呢？though意为：尽管；unless意为：除非；since意为：既然；because意为：因为。because语气最强，表直接原因，可用于回答 why 提出的问题。since所表示的原因已为人们所知，即对已知事实提供理由，而不是表示直接原因。根据句意及since的用法可知，选C。
(5) 让步状语从句的引导词
 

连词	词义	例句
though/although	虽然,尽管	Though/Although he is rich, he lives a simple life.
even though/even if	即使	Even if/though we fail, we will not stop trying.
whenever	无论何时	Whenever you need some help, give me a call.
however	无论如何	However difficult the task is, we must complete it.
whatever	无论什么	Whatever you do I'm behind you.

【经典例题20】(2019重庆A卷) He could find the way home ____ he was only three years old.
A. though            B. because            C. where            D. if
【答案】A
【解析】考查时间状语从句。句意：尽管他只有三岁，但他能找到回家的路。根据空格前后内容之间可知，前后句是让步关系，用though，选A。 
(6) 结果状语从句的引导词

连词	词义	例句
so...that...	如此……以至于……	The bag was so heavy that he couldn't lift it up.
such...that…	如此……以至于……	She is such a lovely girl that everyone likes her.

【经典例题21】(2019江苏连云港) StorySign is ___________ a useful app __________ it can make it easier for deaf children and their parents to read bedtime stories.
A. so ... that            B. such ... that             C. too ... to             D. as ... as
【答案】B
【解析】考查时间状语从句。句意：StorySign是一款如此有用的应用，它能让聋的孩子和他们的父母读睡前故事变得更加简单。so+adj/adv+that+...，意为：如此……以至于……；such+ (a/an)+adj+名词+that+...意为：如此……以至于；too + adj/adv +to do...意为：太……而不能……；as+adj/adv原级+as...意为：和……一样。根据a useful app可知，需套用结构such+a adj+可数名词单数+that...，译为：……如此有用的一个应用以至于……，选B。