1. Định nghĩa: Liên từ là từ dùng để nối các từ loại, cụm từ hay mệnh đề.

2. Phân loại:Liên từ được chia làm hai loại chính:

a. Đẳng lập (song song):

Dùng loại liên từ này để nối những các từ loại hoặc cụm từ/ nhóm từ cùng một loại, hoặc những mệnh đề ngang hàng nhau (tính từ với tính từ, danh từ với danh từ ...):

Ví dụ:

He and I are students.

She is beautiful and kind.

They are learning to read and write.

b. Liên từ phụ thuộc:

Loại liên từ phụ thuộc nối kết các nhóm từ, cụm từ hoặc mệnh đề có chức năng khác nhau - mệnh đề phụ với mệnh đề chính trong câu.

3. Những liên từ Đẳng lập (song song):

Những liên từ Đẳng lập gồm:

AND

Ví dụ: She is a good and loyal wife.

I have many books and notebooks.

BOTH ... AND

Ví dụ: She is both good and loyal.

They learn both English and French.

AS WELL AS

Ví dụ: He has experience as well as knownledge.

NO LESS THAN

Ví dụ: You no less than he are very rich.

NOT ONLY ... BUT (ALSO)

Ví dụ: He learns not only English but but (also) Chinese.

I like playing not only tennis but (also) football.

OR

Ví dụ: Hurry up, or you will be late.

EITHER...OR

Ví dụ: He isn't either good or kind.

I don't have either books or notebooks.

NEITHER ... NOR

Ví dụ: He drinks neither wine nor beer.

She has neither husband nor children.

BUT

Ví dụ: He is intelligent but very lazy.

She is ugly but hard-working.

THEN

Ví dụ: You have eaten nothing; then you must be very hungry.

The plant looks very faded; then it hasn't been watered for long.

CONSEQUENTLY

Ví dụ: You didn't work hard for this term; consequently, he failed the exam.

HOWEVER

Ví dụ: He is a very lazy student; however, he can pass all the exams easily.

It was raining very hard; however, we went out without umbrellar.

NEVERTHELESS

Ví dụ: She studies very hard; nevertheless, she always gets bad marks.

STILL, YET

Ví dụ: I speak to you peaceably; still/yet you will not listen.

She says she does not love me, yet, I still love her.

OR, ELSE, OTHERWISE

Ví dụ: We have to work hard, or/else/otherwise we will fail the exam.

ONLY

Ví dụ: Go where you like; only do not stay here.

THEREFORE

Ví dụ: He violated the traffic signs, therefore he was punished.

4. Những liên từ phụ thuộc (chính phụ):

Những liên từ phụ thuộc:

FOR

Ví dụ: He will surely succeed, for (because) he works hard.

WHEREAS

Ví dụ: He learns hard whereas his friends don't.

Wise men love truth whereas fools avoid it.

WHILE

Ví dụ: Don't sing while you work.

Don't talk while you eat.

BESIDES, MOREOVER

Ví dụ: We have to study hard at school; besides, we must pay attention

to physical exercise.

He stole two watches; moreover, he broke the window.

SO

Ví dụ: He is a good teacher; so, he is very popular with students.

It rained very hard; so, we didn't go out that night.

HENCE

Ví dụ: I had not money about me; hence I did not buy the book.

He came late; hence, he missed the first part of the lesson.

- Liên từ nối mệnh đề (như trạng ngữ):

a. Thời gian (Time):

AFTER

Ví dụ: A man shoud take a little rest, after he has worked hard.

The ship was checked carefully after she had been built.

AS

Ví dụ: He came her, as the clock struck six.

They left as the bell rang..

AS SOON AS

Ví dụ: I will phone you as soon as I come home.

They will get married as soon as they finish university.

BEFORE

Ví dụ: Don't count your chickens before they are hatchd.

He talks as if he were very wise.

.

Ví dụ: He has been very weak, since he was taken sick.

AS LONG AS

Ví dụ: No one can harm us, as long as we remain friends.

I will lend you some money as long as you promise to pay me back.

UNTIL

Ví dụ: People do not know the value of health until they lose it.

WHEN

Ví dụ: When you visit this country, you should bring thick winter clothes.

WHILE

Ví dụ: Make hay while the sun shines.

Step while you dance.

b. Nơi chốn (Places):

WHERE

Ví dụ: The bed room is the best place where I do my homework.

WHEREVER

Ví dụ: His mother follows him wherever he goes.

I will go wherever to find a suitable job for me.

c. Thể cách (Manner):

AS

Ví dụ: Do as I told you to do.

AS IF

Ví dụ: He talks as if he knew everything about her.

He dances as if he were a professional dancer.

d. So sánh (Comparisons):

AS

Ví dụ: He is as tall as his brither.

This bag is as expensive as that one.

THAN

Ví dụ: She is more beautiful than her sister.

She looks fatter than his friend.

e. Lí do (Reasons):

AS

Ví dụ: As it rained very hard, we stopped they games.

BECAUSE

Ví dụ: We could not pass the test because we didn't learn hard.

I didn't meet her because she had left earlier.

SINCE

Ví dụ: I must go since she has telephoned three times.

f. Mục đích (Purposes):

THAT

Ví dụ: I work hard that I may succeed in life.

SO THAT

Ví dụ: We went very early so that we could catch the last bus.

IN ORDER THAT

Ví dụ: We learn French in order to study in France .

g. Điều kiện (Conditions) :

IF

Ví dụ: I will phone him if I have his phone number.

UNLESS (IF NOT)

Ví dụ: You will be late unless you set off now.

Unless you work hard, you will not pass the eams.

PROVIDED THAT

Ví dụ: I will pardon him provided that he acknowledge his fault.

You can enter the room provided that you have the ticket..

IN CASE

Ví dụ: You should take an umbrella in case it rains.

Please take a map with you in case (that) you may get lost.

h. Sự tương phản, trái ngược:

ALTHOUGH, THOUGH, EVEN THOUGH

Ví dụ: Though/even though /although it rained hard, I went out with her.

AS

Ví dụ: Rich as he is, his isn't ever happy.

EVEN IF

Ví dụ: Even if my watch is right, we will be too late.

NOT WITH STANDING THAT