(1)接時間點：如 I have stayed in that country since 1995. 要求：謂v.用現在完成時，而且須是延續性動詞。
接壹段時間 + ago：如 They have lived in that house since two years ago. 要求：謂v.用現在完成時，而且須是延續性動詞。
接時間狀語從句：如 I have loved her since I met her last time. / Lily has stayed at home since she left school. 要求：主句的謂v.用現在完成時，而且須是延續性動詞；從句的謂v.用壹般過去時，而且須是終止性動詞。
(4)用於句型“It’s / It has been + 壹段時間 + since + 時間狀語從句”中，譯作“自從…以來, 已經…(時間)了”。如 It’s / has been three months since he moved to this city. 要求：主句的謂v.用壹般現在時或現在完成時；從句的謂v.用壹般過去時，而且須是終止性動詞。
(5)用於句型“壹段時間 + has passed since + 時間狀語從句”中，譯作“自從…以來, … (時間)已經過去了”。如上個例句還可寫成：Three months has passed since he moved to this city. 要求：主句的謂v.用現在完成時，而且動詞必須是has passed；從句的謂v.用壹般過去時，而且須是終止性動詞。
(6)註：當since用於否定句時，主句的謂v.可以是終止性動詞。如 He hasn’t seen the film since last month.
(7)相關詞組：“從那時起”：ever since、since then、from then on. 註：ever since作為壹個詞組，放句尾可單獨使用。如I have given up smoking ever since. 另外，還可在since後接句子。since前加ever，只是加重語氣而已。如 I have given up smoking ever since I caught a bad cough.
(8) since還可引導原因狀語從句，譯作“由於；因為”，相當於because。如 Since he was lazy, he didn’t finish his homework.
therefore adv.因此, 所以=for that reason=consequently常用於連接兩個並列分句，其前加“and”或分號“;”。
He was ill, and therefore could not come. 他病了, 所以未能來。
He has broken his leg and therefore he can't walk.他摔壞了腿，因此不能走路了。
We do not have enough money. Therefore we cannot afford to buy the new car.我們的錢不夠,因此買不成這輛新車。
so conj. adv因而, 所以, 結果是
It was late, so we went home. 天晚了, 所以我們就回家去了。
He was sick, so they were quiet.他病了，所以他們很安靜。
hence adv.因此, 從此
The town was built among the hills, hence the name Hilltown. 該城鎮修建在群山之中,故取名'山城'。
It is very late; hence you must go to bed.時間已經很晚了，因此妳必須睡覺去。(記住前面是分號，而不是逗號)
then adv因此，就 Go into the cave, then they won't see you. 躲進洞裏去，那他們就看不到妳了。
5、accordingly adv.因此, 從而;所以，因此結果;因此(偶作連詞使用conj.)
He was asked to leave the city and accordingly he went.有人叫他離開該城市,所以他就走了。 You may arrange accordingly.妳可以權宜處理。
Mr Foster has never been to China. Consequently / Hence he knows very little about it.福斯特先生從未去過中國,所以對中國了解得很少。
My car was broken down and consequently I was late. = in consequence
Thus adv.如此，像這樣;因此;於是
He sold his farm and thus he had enough money for his journey.他賣掉了農場，這樣他就有足夠的錢旅行了。
There has been no rain - thus, the crops are drying.天沒下雨，因此莊稼要枯死了。
already 和yet的區別用法
already 和yet都是表示時間的狀語副詞。都表示“已經”，也都用於完成時。但already 壹般用於肯定句中而yet壹般用於否定句和疑問句中。
eg : I have already finished my homework . 我已經完成我的作業了。
Have you finished your homework yet ? 妳已經完成作業了嗎？
No , I haven’t finished it yet. 不，沒完成。
as可用作連詞，引導比較、時間、原因及方式等四種狀語從句，應註意的是，引導的比較狀語從句往往有省略;引導的時間狀語從句壹般用壹般現在時而不用壹般將來時;引導原因狀語從句時與“Because”和“since”引導的從句比較起起來語氣最弱。
as作介詞，意思時“作為”，“以……身份”。例如:He came to China as a tourist five years ago.
而表示像…壹樣時，like通常作介詞用，而介詞後面通常接名詞，代名詞和動名詞。
as in Australia“和在澳大利亞壹樣”。
as……as AS +adj(原級)+AS AS +adv(原級)+AS
as soon as 壹……就 as soon as possible 盡可能快地 as early as possible 盡可能早的
as carefully as you can 盡可能認真地
1。as是連詞，表示“隨著”的意義。lives是life的復數，意義是“生活”。
2。as是連詞，表示“因為，由於”的意義。wanting是現在分詞，表示主動意義，wanting to buy cars=who want to buy cars。
As的用法小結 as可以作連詞、介詞及關系代詞和副詞。現將其用法小結如下:
、 as作連詞的用法: 1.作“在-------期間，當----的時候”引導時間狀語從句.註意與when、 while的用法區別。 ①下列情形時,只用as, 而不用when或while。 1)用於表示同壹個人的兩種動作交替進行,指壹邊----壹邊. 如: The girl sings as she goes to school. He looked behind occasionally as he went forward in the forest. 2)表示兩個同步發生的動作或行?意思是隨著-----的發展.如: As time went on / by, she became more and more beautiful . As children get older, they become more and more interested in everything. 3)表示兩個短暫行為或事情幾乎同時發生.如:I watched her as she read the book. I thought of it just as you opened your mouth. Just as the flying worm hit her face, she gave a loud cry. 4)接在名詞後面表示某壹個年齡段時.如: As a young man, he was active in sports. ②when作"當……的時候"解,可以指較短的(壹點)時間,也可指壹段時間。如:When I was at college, I could speak several foreign languages. When the clock struck twelve, I had slept for 2hours. ③ while常表示壹段較長的時間或壹個過程,強調主句謂語動詞與從句謂語動詞同時發生。如:Work while you work. Play while you play.
As =Since 作"既然"、"由於"解,引導原因狀語從句,常用來表示已為人們所知或顯而易見的原因或理由。如: As he’s been ill for ages, I will help him. As / Since you're not feeling well, you may stay at home. As he wasn't ready , we went without him.
As =in the way that作"像"、"按照……的方式"解,引導方式狀語從句。如: Do as I told you. Remember, you must do everything as I do.
用於as--- as或not / so/ as ---- as中,前壹個as是副詞,後壹個as是連詞,引導比較狀語從句。如:They helped the old as much as possible. I don't speak English so/ as well as she does.
表示雖然,盡管 等,引導讓步狀語從句,常用倒裝語序,模式為: adj. /adv. / n.+as +主語+謂語+主句。如: Young as he is, he knows much. Tired as they were, they walked on.
表示也------壹樣。 She is a doctor, as was her husband. (二)、 as作關系代詞,引導定語從句,表示正如,這壹點.如: He is very careful, as we all know. As is well-known, Taiwan belongs to China. 另外,當先行詞被the same, such等詞修飾時,常用as來引導定語從句。如: Such a clever girl as she can learn anything quickly. I was reading the same book as he bought yesterday.
as作介詞的用法. 1.表示好像。如:He dressed as a policeman. 2. 表示作為當作。如:I found a job as a guide. 3. 當某人是某身份時。如:As a child , she was sent to abroad. 4. as引導的介詞短語大多用作狀語,as譯為"作為";少數情況可引起賓語補足語。如: As a Party member, I'll take the lead in everything. (狀語) She works as a model. (狀語) She has me as one of her best friends.(引起賓語補足語) (
作副詞的用法 1 表示與------等同。如:This dress is twice as expensive as that one. 2 像，如等。如:As before, he remained unmoved.
although 與 though的用法區別
用作連詞 表示“雖然”，兩者大致同義，可換用，只是 although 比 though 更為正式: Though [Although] it was raining，we went there. 雖然下著雨，但我們還是去了那兒。
Though [Although] it was barely four o’clock, the lights were already on. 盡管才四點鐘，燈已經亮了。
Though [Although] we are poor, we are still happy. 我們雖然窮，仍然很快活。
二、用作副詞 although 壹般不用作副詞，而 though 可用作副詞，且壹般放在句末(不放在句首)，意為“可是”、“不過”:
It’s hard work; I enjoy it though. 工作很辛苦，可是我樂意幹。
He is looking fit, though. 但他看起來很健康。
You can count on him, though. 不過妳可以指靠他。
三、用於習語 在 as though(好像，仿佛)，even though(即使，縱然)等固定短語中不能用 although:
She closed her eyes as though she were tired. 她閉上眼，仿佛很疲勞似的。
We felt as though we had witnessed the whole thing. 我們感到仿佛目擊了整個這件事似的。
He is an honest man, I must say, even though I have opposed him. 盡管我反對過他，我還得說他是壹個誠實的人。
She was always afraid of men, even though she had lots of boyfriends.盡管她有很多男朋友，她總是害怕男人。
四、用於倒裝 though 引導的讓步狀語從句可用部分倒裝的形式(註意:倒裝後位於句首的名詞之前不用冠詞)，但 although 壹般不這樣用:
Poor though I am, I can afford it. 我雖窮，但這東西還是買得起的。
Child though he was, he did quite well. 他雖是孩子，但幹得很好。
另外註意: 1. although較正式，語氣強 Although he was tired, he went on working.
2. although引導的從句放在主句前後均可，有時還可放在句中。
Although many difficulties are still ahead, we are determined to make greater achievements. 盡管在前面的道路上還有許多困難，但是，我們決心要取得更大的成就。
He often helps me with my English although he is quite busy. 盡管他相當忙，但是還常常幫我學英語。
3. although引導的從句不能與but, however連用，但可與yet, still連用。
不能說:Although he was old, but he worked hard. 應把but去掉。
當然，保留but而去Although也可。 註意:although 的幾不: although不能指假設的情況 although不能作並列連詞 although不能作副詞，放在詞尾常用連詞介紹.