1.定義：連接兩個(gè)句子的單詞或短語(yǔ)；
2.?用法：
(1)并列連詞：and, but, or;
①and ”和，而且”玩敏，前后狀況一樣或相似；用于肯定句付魔；
e.g. Tom likes basketball and I also like basketball.
? ? ? ? Tom is outgoing and hardworking.
? ? ? =Tom is outgoing and he is also hardworking.
?? ②but “但是”,表示轉(zhuǎn)折，前后狀況不一樣或是相反飞蹂；
???? e.g. Tom likes basketball, but I like baseball.
? ? ? ? ? ? ?Tom is hardworking, but he is careless.
?? ③or “或者”几苍，表示選擇關(guān)系；通常用于否定句和一般疑問(wèn)句陈哑；
???? e.g. Tom doesn’t like apples or oranges.
? ? ? ? ? ? Would you like to drink, juice or water?
④and和or 的特殊用法：
and表示遞進(jìn)妻坝，“這樣做的話(huà)，就會(huì)怎么樣”惊窖，結(jié)構(gòu)為“祈使句刽宪，and+句子（用將來(lái)時(shí)）”；
??? e.g.Work hard, and you will get good grades.
? ? ? ? ? ?Stay here, and you will know the truth.
or表示否則界酒，“這樣做的話(huà)圣拄，否則會(huì)或不會(huì)怎么樣”，結(jié)構(gòu)為“祈使句毁欣，or+句子（用將來(lái)時(shí)）庇谆。
e.g. Work hard, or you won’t get good grades.
? ? ? ?Take the umbrella, or you will get wet.
(2)時(shí)間連詞：when, while, as, since, before,after, as long as等岳掐。
?①when, while和as都意為“當(dāng)……的時(shí)候”；引導(dǎo)時(shí)間狀語(yǔ)從句饭耳；
?②when引導(dǎo)的從句謂語(yǔ)動(dòng)詞可以為延續(xù)性動(dòng)詞和非延續(xù)性動(dòng)詞串述；
?③while引導(dǎo)的從句謂語(yǔ)動(dòng)詞必須為延續(xù)性動(dòng)詞，通常用于進(jìn)行時(shí)寞肖；
?④as引導(dǎo)的從句謂語(yǔ)動(dòng)詞通常為延續(xù)性動(dòng)詞纲酗，通常用于進(jìn)行時(shí)；還可以表示“一邊……一邊……”新蟆。
e.g. I am doing my homework when Tom comes back.
? ? ? ?I was doing my homework while/when /as my mother was doing breakfast yesterday morning.
? ? ? ?Tom is reading a book as he is listening to music now.
⑤since意為“自從”觅赊，引導(dǎo)的時(shí)間狀語(yǔ)從句用過(guò)去時(shí)，主句用現(xiàn)在完成時(shí)栅葡；
?e.g. Tom has lived in Kunming since he came here.
⑥before 意為“在……之前”茉兰；反義詞after”在……之后”，均引導(dǎo)時(shí)間狀語(yǔ)從句欣簇；
?e.g. Tom had lived in Kunming before he began to learn English.
? ? ? ? ?She has studied French after she made the decision.
⑦as soon as意為“一……就……”, 主句通常用將來(lái)時(shí)规脸，從句用一般現(xiàn)在時(shí)。
e.g. I will call you as soon as I arrive in Beijing.
(3)其它常見(jiàn)連詞：
①if 和unless(= if not),引導(dǎo)條件狀語(yǔ)從句熊咽，時(shí)態(tài)遵循“主將從現(xiàn)”莫鸭；
e.g. You will get good grades if you work hard.
? ? ? ? Everything will get worse unless we take action at once.
②either…or…“要么……要么……”,表示兩者中選其一；謂語(yǔ)動(dòng)詞單復(fù)數(shù)取決于就近原則横殴；
? ? neither…nor…”既不……也不……”被因，表示兩者都不選；謂語(yǔ)動(dòng)詞單復(fù)數(shù)取決于就近原則衫仑；
? ? not only…but also…”不但……而且……”梨与，謂語(yǔ)動(dòng)詞單復(fù)數(shù)取決于就近原則；
? ? both…and…“兩者都”文狱，表示兩者都選粥鞋，作主語(yǔ)為復(fù)數(shù)。
??e.g.Either you or Tom plays the role.
? ? ? ? Neither Tom nor I am not students.
? ? ? ? ?Not only Tom but also other students in my class are hardworking.
? ? ? ? ?Both Tom and you are good students.
③though, although, even if, even though意為“雖然”瞄崇，不與but連用呻粹，但可以與yet(但是)連用，引導(dǎo)讓步狀語(yǔ)從句苏研；
??e.g. Though Tom is eight years old, he can speak English well.
④because意為”因?yàn)椤钡茸牵龑?dǎo)原因狀語(yǔ)從句；so意為“因此”摹蘑，引導(dǎo)結(jié)果狀語(yǔ)從句筹燕；注意because不能與so連用；
?e.g.Tom went to school late because he got up late.
? ? ? ?Tom got a cold so he should go to see the doctor.
⑤till, not…until意為“直到……才…”,引導(dǎo)時(shí)間狀語(yǔ)從句；
e.g. Tom didn’t come back home until I finished my homework.
⑥ as long as”只要”庄萎；
e.g. As long as you stay here, you will know the thing.
⑦while和but都表轉(zhuǎn)折時(shí)的區(qū)分：but只表示前后狀況相反或不一樣踪少，而while表轉(zhuǎn)折時(shí)有鮮明對(duì)比在里面；
e.g. Some people are rich while/but others are poor.
⑧since意“因?yàn)椤笨诽危喈?dāng)于because;意為“既然”援奢，相當(dāng)于now that。
e.g. Since she said like this, I think we should believe her.
? ? ? ?Don’t criticize him like that since he is only a child.
