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Cấu trúc câu điều kiện loại 1 2 3 và các chú ý ở mệnh đề điều kiện If

Cấu trúc của câu điều kiện là một kiến thức quan trọng xuất hiện nhiều trong chương trình học. Đây cũng là một chủ điểm ngữ pháp thường gặp trong thi cử và giao tiếp.

Câu điều kiện gồm có hai phần : một  mệnh đề mở đầu bằng “If” (If -clause) được gọi là mệnh đề điều kiện  và một mệnh đề chính (main clause) được gọi là là mệnh đề kết quả.

Ex: If it rains, I will stay at home

Or   I will stay at home if it rains.

Có ba loại câu điều kiện: 

cau-truc-cau-dieu-kien-cac-loai-va-nhung-dieu-can-chu-y-o-menh-de-if-voh
Trong tiếng Anh có ba loại câu điều kiện

1. Conditional sentences Type1 ( Câu điều kiện loại 1)

1.1. Cách dùng (Use)

Chúng ta dùng câu điều kiện lọai 1 để diễn tả hành động hoặc tình huống có thể xảy ra ở hiện tại hoặc tương lai.

1.2. Cấu trúc câu điều kiện loại 1 (Form)

[ If- Clause  : Present simple ]  +  [ Main Clause  : will/ can/ may + bare infinitive ]

Ex : If it rains, we will go to the cinema.

If the sun shines, we will go to the beach.

1.3. Một số biến thể của dạng cơ bản

Ngoài thì hiện tại đơn (Present simple), chúng ta có thể dùng thì hiện tại tiếp diễn (Present continuous) hoặc thì hiện tại hoàn thành (Present perfect) trong mệnh đề “If”.

Ex: If you are waiting for a bus, you should join the queue.

If you are staying for another night, I’ll ask the manager to give you a better room.

If you have finished your homework, you can go out.

Chúng ta có thể dùng câu yêu cầu với dạng câu cầu khiến (Imperative) hoặc với “should” trong mệnh đề chính.

Ex : If you need help , please let me know.

If you’re tired, you should take a rest.

Chúng ta có thể dùng thì hiện tại đơn (Present simple) trong mệnh đề chính khi nói về sự thật hiển nhiên; tình huống xảy ra một cách tự động hoặc thường xuyên theo thói quen. Loại câu điều kiện này được gọi là “The Zero Conditional”.

Ex : If water is colder than 0 ¨Celsius, it freezes.

If you press this button, the machine stops.

If I go to bed late, I feel bad.

2. Conditional sentences Type2 (Câu điều kiện loại 2)

2.1. Cách dùng (Use)

Chúng ta dùng câu điều kiện loại 2 để diễn tả hành động hoặc tình huống không có thật và không thể xảy ra ở hiện tại hoặc tương lai .

2.2.Cấu trúc câu điều kiện loại 2 (Form)

[ If- Clause  : Past simple ]  +  [ Main Clause  : would / could /might + bare infinitive ]

Ex: If I were you , I would plant some trees around the house. ( But I am not you .)

If I lived near my office, I would be in time for work. ( But I don’t live near my office. )

Chú ý:

Chúng ta thường dùng “were” đối với động từ  “be” cho tất cả các ngôi trong câu điều kiện loại 2. Hình thức “was” cũng có thể dùng với chủ ngữ số ít , nhưng được xem là cách dùng bình dân trong văn nói (informal). Do đó, tốt nhất là dùng “were” cho tất cả các tình huống.

Chúng ta dùng “might” trong mệnh đề chính khi diễn tả ý nghĩa có lẽ và dùng “could” khi diễn tả ý nghĩa có khả năng.

2.3. Một số biến thể của dạng cơ bản

Thay vì dùng thì quá khứ đơn (Past simple) trong mệnh đề “If”, ta có thể dùng thì quá khứ tiếp diễn (Past continuous).

Ex: (We’re going by air and)  I hate flying. If I were going by boat, I’d feel much happier.

If my car were working, I could/ would drive you to the station. 

Thay vì dùng thì quá khứ đơn trong mệnh đề “If ”, chúng ta có thể dùng were + to –infinitive để nhấn mạnh ý không thể xảy ra.

Ex: If I were to win one million dollars, I’d give up my job.

(= If I won one million dollars, … )

If he were to offer you the job, would you accept it ?

(= If he offered you the job, … )

Thay vì dùng dạng điều kiện đơn trong mệnh đề chính, ta có thể dùng dạng điều kiện tiếp diễn. 

Ex : Peter is on holiday; he is touring Italy. – If I were on holiday, I would/ might be touring Italy too.

3. Conditional sentences Type3 (Câu điều kiện loại 3)

3.1. Cách dùng (Use)

Chúng ta dùng câu điều kiện loại 3 để diễn tả hành động hoặc tình huống không thể xảy ra hoặc đã xảy ra theo một cách khác trong quá khứ.

3.2. Cấu trúc câu điều kiện loại 3 (Form)

[ If- Clause  : Past perfect ]  +  [ Main Clause  : would / could /might + have + Past participle ]

Ex: If I had known that you were coming, I would have met you at the airport.

(But I didn’t know, so I didn’t come.)

If we had found him earlier, we could/ might have saved his life. 

3.3. Một số biến thể của dạng cơ bản

Ta có thể dùng thì quá khứ hoàn thành tiếp diễn (Past perfect continuous tense) trong mệnh đề “If”.

Ex: I was wearing a seatbelt.  If I hadn’t been wearing one, I’d have been injured.

Ta có thể dùng dạng tiếp diễn của những thì thuộc dạng hoàn thành trong mệnh đề chính (The conditional form of the perfect conditional).

Ex: At the time of the accident I was sitting in the back of the car, because Tom’s little boy was sitting beside him in front.  If Tom’s boy hadn’t been there, I would have been sitting in front.

Ta có thể dùng dạng câu pha trộn (Mixed Type) giữa câu điều kiện loại 2 và loại 3.

Types If – clause

Main clause

Mixed type 1

Past prefect (had + V-ed/ V3) (Type 3)

would/ could/ might + V ( bare-inf.)(Type 2)

Mixed type 2

Past simple (V-ed/ V2)

(Type 2)

would / could/ might + have + V-ed/ V3

(Type 3)

Ex:

a/ If you hadn’t stayed up too late last night, you wouldn’t feel tired now.

(You stayed up late last night, so you feel tired now.)

If you had warned me, I wouldn’t be in great trouble now.

(You didn’t warn me, so I am in great trouble now.)

If she loved him, she would have stayed with him.

(She doesn’t love him, so she left him)

4. Dùng dạng đảo ngữ (Inversion) thay cho mệnh đề “If-clause” khi muốn nhấn mạnh

Type 1: Should + S + V (bare infinitive), …  

Ex: Should you know anything about the murder, phone the police. 

(= If you know anything about the murder, phone the police.)

Type 2: Were + S + to-infinitive, …

Ex: Were I to fly in a spaceship, I would be extremely excited.

(If I were to fly in a spaceship, …)

Type 3: Had +  S + V-ed/ V3, …  

Ex: Had I heard about his trouble, I would have come to help him.

(= If I had heard about his trouble, I would have come to help him)

5. Một số từ khác có thể được sử dụng thay cho If trong mệnh đề điều kiện

unless = if … not   (nếu không, trừ khi )

Ex: Unless you start at once, you’ll be late.

=  If you don’t start at once, you’ll be late.

Unless you had a permit, you couldn’t have a job.

= If you didn’t have a permit, you couldn’t have a job.

provided /providing (that); on condition (that); as long as; so long as (với điều kiện là, miễn là)

Ex: I will agree to go provided / providing (that) my expenses are paid.

Provided that everyone agrees, we’ll have the meeting on Tuesday.

You can use my car as long as you drive carefully.

You can go out on condition that you wear an overcoat.

(just) suppose/ supposing (that) (giả sử)

Ex: Just suppose it didn’t rain for four months, would we have enough water ?

but for = if it were not for/ if it hadn’t been for: nếu không (có) 

Ex: My father pays my fees. But for that I wouldn’t be here.

The car broke down. But for that we would have been in time .

6. Practice

Câu 1: Put the verbs in brackets into the correct tenses.

1. If I find your passport, I (telephone) you.

2. If she (need) a radio, she can borrow mine.

3. Ice ( turn ) to water if you heat it.

4. Should you require anything else, please (ring) the bell for the attendant.

5. I shouldn’t drink that wine if I (be) you.

6. He might get fat if he (stop) smoking.

7. But for the fog, we (reach) our destination ages ago.

8. If I (had) a map, I would have been all right.

9. What would you do if the lift (get) stuck betwwen two floors ?

10. If we had more rain, our crops (grow) faster.

11. If you pass your exam, we (have ) a celebration.

12. The machine stops automatically if something (go) wrong.

13. I (give ) you £100 provided that you say nothing about this.

14. If you’d stayed at home, there ( not be) any trouble.

15. It’s a pity David isn’t here. He (be) very amused.

Đáp án:

1. If I find your passport, I will telephone you.

2. If she needs a radio, she can borrow mine.

3. Ice turns/ will turn to water if you heat it.

4. Should you require anything else, please ring the bell for the attendant.

5. I shouldn’t drink that wine if I were you.

6. He might get fat if he stopped smoking.

7. But for the fog, we would have reached our destination ages ago.

8. If I had had a map, I would have been all right.

9. What would you do if the lift got stuck between two floors ?

10. If we had more rain, our crops would grow faster.

11. If you pass your exam, we will have a celebration.

12. The machine stops automatically if something goes wrong.

13. I will give you £100 provided that you say nothing about this.

14. If you’d stayed at home, there wouldn’t have been any trouble.

15. It’s a pity David isn’t here. He would be very amused.

Câu 2: Rewrite the following sentences, using the conditionals.

1. Read the passage twice or three times or you won’t understand it.

You won’t ...

2. Unless you tell me the reason , I won’t leave.

If ...

3. You press this button to stop the machine .

If ...

4. Water these plants or they will wither.

Unless ...

5. If it doesn’t rain, we will go swimming.

Unless ...

6. You don’t work overtime, so you don’t earn as much as I do.

If ...

7. We have no ladder, so we can’t get over the wall. 

If ...

8. Our heating isn’t working today and I feel cold.

If ...

9. We didn’t have a map, so we got lost. 

If ...

10. I didn’t take a taxi because I didn’t have any money on me.

If ...

11. The driver wasn’t injured in the crash because he was wearing a seat belt.

If ...

12. We didn’t hurry, so we missed the train.

If ...

13. You didn’t listen to my advice, so you are in trouble now.

If ...

14. Dick is in prison because a detective recognized him.

If ...

15. If anything wrong happens, let  me know at once.

Should ...

16. If the weather were better, they could go for a walk.

Were ...

17. If the teacher knew about it, we would be in real trouble.

If the teacher were ...

18. But for his help, she would have failed in the driving test.

If ...

19. Our team didn’t lose the match thanks to the goalkeeper.

If it ...

20. I didn’t notice you. That’s why I didn’t greet you.

Had ...

Đáp án:

1. Read the passage twice or three times or you won’t understand it.

You won’t understand the passage if you don’t read it twice or three times.

2. Unless you tell me the reason, I won’t leave.

If you don’t tell me the reason, I won’t leave.

3. You press this button to stop the machine .

If you press this button, the machine stops / will stop.

4. Water these plants or they will wither.

Unless you water these plants, they will wither.

5. If it doesn’t rain, we will go swimming.

Unless it rains, we will go swimming.

6. You don’t work overtime, so you don’t earn as much as I do.

If you worked overtime, you would earn as much as I do.

7. We have no ladder, so we can’t get over the wall. 

If we had a ladder, we could get over the wall.

8. Our heating isn’t working today and I feel cold.

If our heating were working today, I wouldn’t feel cold.

9. We didn’t have a map, so we got lost. 

If we had had a map, we wouldn’t have got lost.

10. I didn’t take a taxi because I didn’t have any money on me.

If I had had some money on me, I would have taken a taxi.

11. The driver wasn’t injured in the crash because he was wearing a seat belt.

If the driver hadn’t been wearing a seat belt, he would have been injured in the crash.

12.We didn’t hurry, so we missed the train.

If we had hurried, we wouldn’t have missed the train.

13. You didn’t listen to my advice, so you are in trouble now.

If you had listened to my advice, you wouldn’t be in trouble now.

14. Dick is in prison because a detective recognized him.

If a detective hadn’t recognized Dick, he wouldn’t be in prison.

15. If anything wrong happens, let  me know at once.

Should anything wrong happen, let me know at once.

16. If the weather were better, they could go for a walk.

Were the weather better, they could go for a walk.

17. If the teacher knew about it, we would be in real trouble.

If the teacher were to know about it, we would be in real trouble.

18. But for his help, she would have failed in the driving test.

If it hadn’t been for his help/ he hadn’t helped her, she would have failed in the driving test.

19. Our team didn’t lose the match thanks to the goalkeeper.

If it hadn’t been for the goalkeeper, we would have lost the match.

20. I didn’t notice you. That’s why I didn’t greet you.

Had I noticed you, I would have greeted you.

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Hy vọng bài viết và các bài tập trên sẽ giúp các em có thể hiểu được cấu trúc câu điều kiện và những điều cần lưu ý quanh mệnh đề If trong tiếng Anh.

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