4. 條件狀語從句引導(dǎo)條件狀語從句的連詞有：if，unless，as / so long as，suppose （that），supposing （that），in case，when等。條件狀語從句可以分為真實條件狀語從句和非真實條件狀語從句。
⑴真實條件句真實條件句表示現(xiàn)實或可能的情況，由if引導(dǎo)，它的主句可以是陳述句，疑問句或祈使句，可置于主句之前或之后。
If you heat ice，it melts. If it rained，I went by bus. unless引導(dǎo)的否定條件狀語從句，在意義上相當(dāng)于if…not，如：
Don‘t come unless I telephone. as / so long as，provided / providing （that）意為“只要、如果”，如：
You can borrow this pen as long as you can keep it well. in case在英國英語中表示目的，在美國英語中可表示條件，意為“如果、萬一”，如：
In case the house burns down，we‘ll get the insurance money.
⑵非真實條件句請參閱第十一章“虛擬語氣”。
5.讓步狀語從句引導(dǎo)讓步狀語從句的連詞有：although，though，even if，even though，if，for all that，when，while，whether…or，whatever，no matter what等。
although和though意義一樣，都作“雖然、即使”解，都表示讓步，一般情況下可互換使用，只是although語氣較重，大多置于句首。如：
They are generous though they are poor. Although he was Japanese，he spent most of his life in China. even if和even though都作“即使”解，兩者可以互換使用，如：
She insisted on her own opinion even though / even if he was wrong. if作“即使、雖然”解，也表示讓步，如：
If he is wrong，he is honest. whether…or作“不論……是否”或“不論……還是”解，如：
You don‘t have to worry me whether I am well or ill.為了強調(diào)讓步意義，在正式文體或文學(xué)作品中，常用as引導(dǎo)讓步從句，從句的補語或狀語置于句首。如：
Tall as he was，he couldn‘t reach the top of the shelf. Strong as you may be，you cannot lift it.詞尾為-ever的wh-詞可以與“no matter + wh-詞”互換使用，作“無論……”解，后者常用于口語中，如：
Whoever / No matter who rings，tell him I‘m out. Wherever / No matter where he is，he will be thinking of you.由whenever，wherever，however引導(dǎo)的從句，也可以分別看作時間狀語從句、地點狀語從句和方式狀語從句。把它們當(dāng)作讓步狀語從句是因為它們常有no matter when （where，how）的含義。
6.原因狀語從句原因狀語從句通常由because，since，as，when now （that），seeing （that），considering （that）等引導(dǎo)。
because，since和as三者的區(qū)別如下：
because的語勢，其次是since，再次是as. because可以回答why引導(dǎo)的特殊問句，而since和as不能。
because引導(dǎo)的從句可以被just，only，simply等副詞修飾，也可以用并列連詞構(gòu)成并列的because從句，而since和as則不能。如：
We pardoned him only because he was still young. for表示原因時，作“因為”解，多用于正式文體，有時可以與because換用，但for從句只能置于主句之后。如：
She didn‘t go to school，for / because she was ill. now （that）和seeing （that）都作“既然”解，通?？膳csince或as換用，如：
Now （that） you have come，you may as well stay. Seeing （that） he is inexperienced，he is not fit for the work. 7. 結(jié)果狀語從句引導(dǎo)結(jié)果狀語從句的連詞有：so that，so…that，such that，such…that，that等。
當(dāng)從句前面有逗號時，so that中that可省略，如：
It was dark，so （that） we could see nothing in front of us.“So + 形容詞 / 副詞 + that”是引導(dǎo)結(jié)果狀語從句的常用結(jié)構(gòu)，如：
He talked so loud that he annoyed the speaker. He was so brilliant that he made a lot of inventions.“such （a） + 形容詞 + 名詞 + that”與“so…that”的意義相同，如：
It was such a hot day that people could not go out. He painted such beautiful pictures that the visitors were lost in admiration. that可以單獨引導(dǎo)結(jié)果狀語從句，如：
The question is of great importance that it cannot be neglected. 8. 目的狀語從句引導(dǎo)目的狀語從句的連詞有：in order that，so that，so，that，in case，for fear that，lest等。
in order that與so that的意義和用法基本相同，in order that多用于正式文體，常表示經(jīng)過認(rèn)真考慮的目的，如：
In order that he would have more space for painting，he bought a big house. You ought to write to him，in order that he won‘t feel we are hiding things from him. So和that可視為so that的省略形式，但不如so that常用，如：
Bring it closer so / that I may see it better. for fear that，in case和lest都表示否定的目的，相當(dāng)于so that…not或in order that…not，作“以免、以防”解。
He wrote the name down for fear that he should forget it . lest限于正式文體，它所引導(dǎo)的從句中的謂語動詞多用should be型或be型虛擬形式，如：
He hid the box lest it （should） be stolen. in case引導(dǎo)的從句謂語既可以用虛擬形式，又可用陳述語氣，如：
Better take more clothes in case it is cold. She doesn‘t dare to go out in case she is recognized / （should） be recognized.
⑴真實條件句真實條件句表示現(xiàn)實或可能的情況，由if引導(dǎo)，它的主句可以是陳述句，疑問句或祈使句，可置于主句之前或之后。
If you heat ice，it melts. If it rained，I went by bus. unless引導(dǎo)的否定條件狀語從句，在意義上相當(dāng)于if…not，如：
Don‘t come unless I telephone. as / so long as，provided / providing （that）意為“只要、如果”，如：
You can borrow this pen as long as you can keep it well. in case在英國英語中表示目的，在美國英語中可表示條件，意為“如果、萬一”，如：
In case the house burns down，we‘ll get the insurance money.
⑵非真實條件句請參閱第十一章“虛擬語氣”。
5.讓步狀語從句引導(dǎo)讓步狀語從句的連詞有：although，though，even if，even though，if，for all that，when，while，whether…or，whatever，no matter what等。
although和though意義一樣，都作“雖然、即使”解，都表示讓步，一般情況下可互換使用，只是although語氣較重，大多置于句首。如：
They are generous though they are poor. Although he was Japanese，he spent most of his life in China. even if和even though都作“即使”解，兩者可以互換使用，如：
She insisted on her own opinion even though / even if he was wrong. if作“即使、雖然”解，也表示讓步，如：
If he is wrong，he is honest. whether…or作“不論……是否”或“不論……還是”解，如：
You don‘t have to worry me whether I am well or ill.為了強調(diào)讓步意義，在正式文體或文學(xué)作品中，常用as引導(dǎo)讓步從句，從句的補語或狀語置于句首。如：
Tall as he was，he couldn‘t reach the top of the shelf. Strong as you may be，you cannot lift it.詞尾為-ever的wh-詞可以與“no matter + wh-詞”互換使用，作“無論……”解，后者常用于口語中，如：
Whoever / No matter who rings，tell him I‘m out. Wherever / No matter where he is，he will be thinking of you.由whenever，wherever，however引導(dǎo)的從句，也可以分別看作時間狀語從句、地點狀語從句和方式狀語從句。把它們當(dāng)作讓步狀語從句是因為它們常有no matter when （where，how）的含義。
6.原因狀語從句原因狀語從句通常由because，since，as，when now （that），seeing （that），considering （that）等引導(dǎo)。
because，since和as三者的區(qū)別如下：
because的語勢，其次是since，再次是as. because可以回答why引導(dǎo)的特殊問句，而since和as不能。
because引導(dǎo)的從句可以被just，only，simply等副詞修飾，也可以用并列連詞構(gòu)成并列的because從句，而since和as則不能。如：
We pardoned him only because he was still young. for表示原因時，作“因為”解，多用于正式文體，有時可以與because換用，但for從句只能置于主句之后。如：
She didn‘t go to school，for / because she was ill. now （that）和seeing （that）都作“既然”解，通?？膳csince或as換用，如：
Now （that） you have come，you may as well stay. Seeing （that） he is inexperienced，he is not fit for the work. 7. 結(jié)果狀語從句引導(dǎo)結(jié)果狀語從句的連詞有：so that，so…that，such that，such…that，that等。
當(dāng)從句前面有逗號時，so that中that可省略，如：
It was dark，so （that） we could see nothing in front of us.“So + 形容詞 / 副詞 + that”是引導(dǎo)結(jié)果狀語從句的常用結(jié)構(gòu)，如：
He talked so loud that he annoyed the speaker. He was so brilliant that he made a lot of inventions.“such （a） + 形容詞 + 名詞 + that”與“so…that”的意義相同，如：
It was such a hot day that people could not go out. He painted such beautiful pictures that the visitors were lost in admiration. that可以單獨引導(dǎo)結(jié)果狀語從句，如：
The question is of great importance that it cannot be neglected. 8. 目的狀語從句引導(dǎo)目的狀語從句的連詞有：in order that，so that，so，that，in case，for fear that，lest等。
in order that與so that的意義和用法基本相同，in order that多用于正式文體，常表示經(jīng)過認(rèn)真考慮的目的，如：
In order that he would have more space for painting，he bought a big house. You ought to write to him，in order that he won‘t feel we are hiding things from him. So和that可視為so that的省略形式，但不如so that常用，如：
Bring it closer so / that I may see it better. for fear that，in case和lest都表示否定的目的，相當(dāng)于so that…not或in order that…not，作“以免、以防”解。
He wrote the name down for fear that he should forget it . lest限于正式文體，它所引導(dǎo)的從句中的謂語動詞多用should be型或be型虛擬形式，如：
He hid the box lest it （should） be stolen. in case引導(dǎo)的從句謂語既可以用虛擬形式，又可用陳述語氣，如：
Better take more clothes in case it is cold. She doesn‘t dare to go out in case she is recognized / （should） be recognized.