引导条件状语从句的连词或词组有: if, unless(除非), as/so long as, on condition that(在......条件下) , provided / providing that从句(假如), suppose/ supposing(假如), in case( 以防, 万一), for fear that (惟恐,以免) , only if(只要,只有)等。

①As long as you are here before 12, you can come to the match with me.

②Students are allowed to enter the computer lab, only if the teacher has given permission.只要老师允许，学生才能进入电脑实验室。

③You can go out to play on condition that you have finished your homework.

④Please take your raincoat along with you in case it rains.

⑤He always slept by the phone in case she rang during the night.

⑥Don't go out tomorrow morning in case Mr Li should come to visit you.

1. if 和unless是最常用的条件从句连接词，unless在意义上等于"if ...not"，并且语气较强。If可用于虚拟条件句，unless则一般不用于虚拟条件句。

①If you keep on practising, you will improve your English .

如果你继续练习的话，你将会提高你的英语。

②He will never make progress unless he works hard.= He will never make progress if he doesn't work hard.

　　　　　　　　　　三、让步状语从句

1. Whatever (whoever, whichever, whenever, wherever，however...) 与no matter what (who, which, when, where, how...) 都可引导让步状语从句，意义无差异，意为: "无论......"

在引导名词性从句时只能疑问词+ever, 引导让步状语从句时疑问词+ever与 no matter +疑问词两者均可。（名词性从句：主语/宾语/表语/同位语从句）

①Whoever (=No matter who) wants to speak to me on the phone, tell him I'm busy. 不管谁打电话给我, 就说我现在正忙着呢。

②However(=No matter how) difficult the task is, I can finish it on time.

★③Whoever will be in charge of the project(主语从句) hasn't been decided yet. 谁来负责这项工程还没有决定。

2.as/though 虽然,尽管, 引导让步状语从句时常用部分倒装语序，表示强调。其倒装形式的基本结构为: 名词/动词/形容词/副词+ as /though+ 主谓结构。倒装时若名词前有冠词, 冠词要省去。

★①Child as/though he is ,he knows a lot.=Although/Though he is a child, he knows a lot 尽管他是个孩子,但他懂的很多。

②Call as/though you may, he will not come.

即使你给他打电话, 他也不会来。

③Popular as/though she is, she still needs to improve.

尽管已很受欢迎,她仍需要努力。