Ngữ pháp và Bài tập Câu Điều Kiện (IF Clause) | Trường Đại học Khoa Học Xã Hội và Nhân Văn, Đại học Quốc gia Hà Nội

CLAUSES AND
PHRASES (MỆNH ĐỀ VÀ CỤM TỪ) CLAUSES OF
CONDITION (MỆNH ĐỀ CHỈ ĐIỀU KIỆN)
1. Mệnh đề điều kiện là mệnh đề phụ chỉ điều kiện, được nối với mệnh đề chính bởi liên từ IF
nên còn được gọi là mệnh đề if (If-clause). Câu có mệnh đề điều kiện được gọi là câu điều kiện (conditional sentence).
 Có 3 loại câu điều kiện được phân theo bảng công thức sau: TYPE MAIN CLAUSE IF - CLAUSE
I. Real in the present or future (có will
thật ở hiện tại hoặc tương lai) can + V (bare-inf.) shall may
Simple Preseent (chỉ một sự thật,
một quy luật hoặc một thói quen)
II. Unreal in the present (không could Past Simple
có thật ở hiện tại) would Past Subjunctive should + V (bare-inf.) (V2; be → were) might
III. Unreal in the past (không có could Past Perfect thật ở quá khứ) would + have + V3 (had + V3) should might
Ex: If I have time, I’ll help you.
If you heat ice it turns/ will turn to
water. If I were you, I would come there.
He would have passed his exam if he had studied hard.
 Mệnh đề điều kiện có thể đứng trước hoặc sau mệnh đề chính. 2. Trong mệnh
đề điều kiện, ta có thể thay liên từ IF bằng UNLESS (nếu... không, trừ phi). Unless
tương đương với ‘If ... not’.
Ex: If you don’t study hard, you’ll fail in the exam.
→ Unless you study hard, you’ll fail in the
exam. If she doesn’t water these trees, they will die.
→ Unless she waters these trees, they will die.
 Khi đổi câu điều kiện IF sang UNLESS, nhớ lưu ý không được đổi mệnh đề IF ở thể khẳng định
sang thể phủ định mà phải đổi mệnh đề chính theo thể ngược lại. 23
Ex: If I have time, I’ll help you.
→ Unless I have time, I won’t help you.
If we had more rain, our crops would grow faster.
→ Unless we had more rain, our crops wouldn’t grow
faster. If I won a big prize in a lottery, I’d build a school for the poor.
→ Unless I won a big prize in a lottery, I wouldn’t build a school for the poor.
 Ta có thể gút lại công thức sau: IF-CLAUSE UNLESS Thể phủ định
khẳng định (mệnh đề chính không thay đổi) Thể khẳng định
khẳng định (đổi động từ trong mệnh đề chính sang thể phủ định)
3. Ta cũng có thể diễn tả câu điều kiện mà không cần dùng IF hay UNLESS bằng cách đảo chủ ngữ ra sau should, were had hoặc
. Lưu ý không được làm với động từ khác.
Ex: If you should run into Peter, tell him he owes me a letter.
→ Should you run into Peter, tell him he owes me a
letter. If they were stronger, they could lift the table.
→ Were they stronger, they could lift the table.
If he had studied hard, he would have passed his exam.
→ Had he studied hard, he would have passed his exam.
4. Provided (that), On condition (that), As long as, so long as (miễn là, với điều kiện là), Suppose,
Supposing (giả sử như), In case (trong trường búp), Even if (ngay cả khi, dù cho)... có thể dùng
thay cho If trong câu điều kiện.
Ex: In case I forget, please remind me of my promise. EXERCISES
I. Put the verbs in brackets into the correct tenses.
1. If I see him, I (give) him a gift.
2. If I had a typewriter, I (type) it myself.
3. If I had known that you were in hospital, I (visit) you.
4. You could make better progress if you (attend) class regularly.
5. If I (know) his telephone number, I’d give it to you.
6. If you (arrive) ten minutes earlier, you would have got a seat.
7. He could get a job easily if he (have) a degree.
8. I shouldn’t have believed it if I (not see) it with my own eyes.
9. If he (study) hard, he can pass the exam.
10. If she had asked you, you (accept)?
11. Rice plants (grow) well if there is enough rain.
12. He might get fat if he (stop) smoking.
13. What you (do) if you found a burglar in your house?
14. If she (not hurry), she may be late.
15. If I (try) again, I think that I would have succeeded.
16. Water (not run) downhill if there were not gravity.
17. If I tell you a secret, you (promise) not to tell it to anyone else?
18. Tell him to ring me if you (see) him. 24
19. The police (arrest) him if they catch him.
20. If you (speak) more slowly, he might have understood you. II. Use UNLESS instead of IF.
1. If you are not careful, you will cut yourself with that knife.
2. If you do not like this one, I’ll bring you another.
3. I’ll not be able to do any work if I do not have a quiet room. 4. late
If she does not hurry, she’ll be .
5. If we had more rain, our crops would be better.
6. The crops would have been ruined if the flood had risen higher.
7. If you had not sneezed, he wouldn’t have known that we were there.
8. If she did her hair differently, she would look quite nice.
9. If John had played for our football team, we would not have lost the game.
10. If I won a big prize in a lottery, I’d give up my job.
III. Make conditional sentences without conjunctions.
1. If I were you, I’d accept the job.
2. If you had told me that he never paid his debts, I wouldn’t have lent him money.
3. If he had known your telephone number he would have rung you.
4. If it were nice, we would go for a walk.
5. I would come to her wedding if I were invited.
6. Would you visit me if I were sent to prison?
7. Would you have written to her if you had known her address?
8. What would you do if today were a holiday?
9. If they had asked me I would have helped them.
10. Scientists think that men could live on the moon if there were air and water on it.
IV. Complete the following sentences.
1. If I were the Prime Minister, I...
2. He could buy a new car if... 3. If I had more time,...
4. If he hadn’t been ill,...
5. They could have passed the exam if they...
6. We could have come with you if we...
7. If her parents had been richer,...
8. If he had come yesterday,... 9. If it hadn’t rained,...
10. The world would be a better place if...
V. Make conditional sentences according to the facts provided.
1. Keep silent or you’ll wake the baby up.
2. Because you don’t leave immediately, I call a policeman.
3. I don’t know her number, so I don’t ring her up.
4. Go right now or you’ll be late for the train.
5. As she is often absent from class, she can’t keep pace with her classmates.
6. I couldn’t write to Alice because I didn’t know her address.
7. I don’t know the answer, so I can’t tell you.
8. We got lost because we didn’t have a map.
9. His friends were so late, so they missed the train.
10. Today isn’t Sunday, so the pupils can’t go swimming.
11. The heavy rain kept everybody from going out.
12. This chair is too heavy for him to move.
13. He had a flu because he went out in the rain last night.
14. The church bells keep me from sleeping.
15. Morning exercises make me feel better.
16. Stop talking or you won’t understand the lesson. 25
17. The boy is so young that he can’t go to school.
18. The fridge keeps the food from spoiling.
19. Why don’t you study hard?
20. Why don’t you stop smoking?
21. Be careful, or you’ll cut yourself with that knife.
22. Be calm, or you’ll make a wrong decision.
23. Without the air, we would die. 24. c
Without a visa, she couldn’t have come to that ountry.
25. Without the sun, man would live in the darkness.
26. Without money, he wouldn’t have bought such a big house.
27. Smoking makes him so weak.
28. It was very cold yesterday, so we couldn’t go swimming.
29. It is very cold, so we can’t go swimming.
30. I didn’t watch T.V last night because I was busy. 26