1.Hỏi về mục đích

- why..............? tại sao.........?

Ex: Why do you want to learn English?

- what ...........for? để làm gì..........?

Ex : what did you buy it for?

- what is the purpose of......? Mục đích của.......là gì?

Ex: what is the purpose of her visit?

2. Diễn tả mục đích

a. For + Noun ( phrase) : để

Ex: He has gone out for dinner

I went to the supermarket for some foods

b. To do.....: để

Ex: He has gone out to eat dinner

Lưu ý : She has been to the post office for buying stamp
---------> câu này sai

She has been to the post office to buy stamp -----------> câu
này đúng

Tuy nhiên có trường hợp ngoại lệ

To be used for doing / to do

Ex : A knife is used for cutting

A knife is used to cut ( cả hai câu đều đúng)

c. In order to do = so as to do

Ex: He finished work early .He wanted to see the football match.

------> H e finished work early in order to see the football
match

+ In order not to do = so as not to do

Ex: We whisper .We didn't want to disturb him.

-------> So as not to disturrb him, we whisper

+ In order for sb/ sth to do : Để cho ai đó / cái gì làm gì

Ex: In order for the lift to work you must press this button

d. with a view to + V_ing : để làm gì , với ý định làm gì

Ex: With a view to preparing this report, I will visit a number
of venues and attended quite a lot of games

e. So that / In order that + S__V ( can , could , may ,
might , will, would)

Ex: I left the letter on the table . I wanted him to see it when
he came in

= I left the letter on the table so that he could see it when he
came in

We were speaking quietly .We didn't want anyone to hear us

= We were speaking quietly in order that no one could hear it

f. For fear that S_V ( should): vì sợ rằng

Ex: I am telling you this for fear that you should make a mistake