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quanghiep2109
2 năm trước
2.Hãy chỉ ra nhận xét sai khi quan sát ánh sáng được phát ra từ ngọn đèn dây tóc A. Đó là chùm sáng phân kỳ B. Trong chùm sáng có vô số tia sáng C. Trong chùm sáng đó có các tia sáng riêng biệt D. Truyền đến mắt ta không phải là chùm sáng đơn lẻ
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Các câu hỏi liên quan

Điền dạng đúng của động từ 1. If she ....................(work) hard, she .....................(pass) the exam. 2. If I ..................(come) soon, I ....................(phone) you. 3. She ...................(feel) sad if you ....................(not, give) her a gift. 4. If Peter ......................(go) to work late again, he .................(be) sacked. 5. No one .........................(know) the truth if you ................(not, reveal) 6. If the boy ....................(eat) that apple, he ....................(be) ill. 7. If you .....................(not, hurry), you .....................(miss) the bus. 8. Tell him about this story if you .........................(see) him. 9. If you ..........................(have) a day off where you..............(go)? 10. If he ..................(cook) the meal himself, help him. 11. If few people .....................(come) to the meeting, please postpone to the other day. 12. If it .......................(not, be) warm this afternoon, we ...................(put off) the game. 13. Your father ...............(pick) you up if you ..................(come) back late? 14. What you ..................(speak) if you ....................(meet) a foreigner? 15. Unless he .................(answer) all my questions, I ...................(not, help) him.  Viết lại câu không đổi nghĩa 1. Turn off all the lights and you will not pay more money.->If ...................................................................... 2. Unless she wears warm clothes, she will have a cold. -> If ................................................................................ 3. Be careful or you may have an accident. -> If .......................................................................................................... 4. phone your parents or you have a trouble. -> If ......................................... 5. Unless she whispers, everyone knows what she is saying. -> If ........................................................................ 6. Stay here and you will feel save. -> If ............................................................. 7. Pay electricity bill today or your electricity will be cut off. -> If ................................................................. 8. Stop smoking otherwise your cough may be worse. -> If ................................................... 9. Unless we use less fossil fuel, they will be run out soon. -> If ........................................................ 10. Unless it stops raining today, we may be faced with a serious flood. -> If ........................................................ 11. Do morning exercises regularly, your body will be fitter.-> If .................................................... 12. Unless we renewable energy, we will have nothing for the future generation. -> If ............................................ 13. The climate will change unless we reduce the use of non-renewable energy. -> If ........................................ 14. Lock all the doors and noone can break into your house. -> If ........................................... 15. Unless we continue hunting polar bears, they will become extinct in near future. -> If .........................................  Cho dạng đúng của động từ trong ngoặc 1. If It (not rain) ………today, they ( go)…………camping. 2. Peter (play) ………soccer with his friends if he (have) …….free time. 3. If Jane (study) ………..harder, she (pass) …………….the entrance exams. 4. David (come and see) ……………….his girlfriend if he (not have to/work) ……..on a night shift. 5. This machine (break) ……..down if it (not use) ……..quite often. 6. Helen (come)…….. to class late if she (not run)…………….fast enough. 7. Giang’s parents (be)……..very happy if she (get) ……….good marks at school. 8. Thomas (visit) …….Ha Long Bay if he (earn) ……enough money. 9. If you (brush) ….your teeth regularly, you ( not have)……….a toothache. 10. If Carol (have) ….enough qualifications for the job she applied, she ( get) ……..it.  Bài tập biến đổi Unless = if …….not. 1. If Andrew is not lazy, he will pass the final examination. (unless) →………………………………………………………………………………………… 2. John will not catch the train unless he runs more quickly. (If) →………………………………………………………………………………………… 3. The tree will die if it isn’t watered every day. (unless) →………………………………………………………………………………………… 4. Life won’t be very easy if we don’t earn lots of money. (unless) →………………………………………………………………………………………… 5. If you don’t practice more often, your English won’t be better. (unless) →………………………………………………………………………………………… 6. Jack will be dismissed if he doesn’t try to work harder. (unless) →…………………………………………………………………………………………

Exercise3: Rewrite the following sentences: 1. Study hard or you won’t pass the exam.=> If………………………………………………………………….. 2. Don’t be impatient or you will make mistakes.=> If…………………………………………………………………….. 3. I only come if they invite me.=> unless………………………………………………. 4. Leave me alone or I’ll call the police.=>Unless………………………………………………………… 5. You must tell me the whole truth or I won’t help you.=> Unless…………………………………………… 6. Don’t tell lies to your boss or you’ll be fired at once.=> If…………………………………………………………  Chia động từ trong ngoặc 1) If I (study) …………………………, I (pass) …………………….. the exams. 2) If the sun (shine) …………………………, we (walk) ………………………… to the town. 3) If he (have) ………………………… a temperature, he (see) ………………………… the doctor. 4) If my friends (come) …………………………, I (be) ………………………… very happy. 5) If she (earn) ………………………… a lot of money, she (fly) ………………………… to New York. 6) If we (travel) ………………………… to London, we (visit) ………………………… the museums. 7) If you (wear) ……………… sandals in the mountains, you (slip) ………………… on the rocks. 8) If Rita (forget) …………… her homework, the teacher (give) ………………… her a low mark. 9) If they (go) ………………………… to the disco, they (listen) ………………………… to loud music. 10) If you (wait) ………………………… a minute, I (ask) ………………………… my parents. Hoàn thành các câu sau đây theo điều kiện loại 1 của những từ trong ( ). 1) If we __________ (to send) an invitation, our friends __________ (to come) to our party. 2) He __________ (not/to understand) you if you __________ (to whisper). 3) They __________ (not/to survive) in the desert if they __________ (not/to take) extra water with them. 4) If you __________ (to press) CTRL + s, you __________ (to save) the file. 5) You __________ (to cross) the Channel if you __________ (to fly) from Paris to London. 6) Fred __________ (to answer) the phone if his wife __________ (to have) a bath. 7) If Claire __________ (to wear) this dress at the party, our guests __________ (not/to stay) any longer. 8) If I __________ (to touch) this snake, my girlfriend __________ (not/to scream). 9) She __________ (to forget) to pick you up if you __________ (not/to phone) her. 10) I __________ (to remember) you if you __________ (to give) me a photo.

Exercise 2: Put the verbs in brackets into the correct forms. 1. What will happen if my parachute (not open)…………………………………? 2. If she (need) …………………………………a radio, she can borrow mine. 3. What you (do) …………………………………when you come to the party tonight? 5. If I lend you 10 dollars, when you (repay) ………………………………… me? 6. Unless you are more careful, you (have) …………………………………an accident. 7. Ice (turn) …………………………………to water if you heat it. 8. Unless I have a quiet room, I (not be able) …………………………………to do any work. 9. He'll be late for the train if he (not go) …………………………………at once. 10. Tell him to phone me if you (see) …………………………………him. 11. If he were in, he (answer) …………………………………the phone. 12. If he worked more slowly he (not make) …………………………………so many mistakes 13. The plants will die unless you (water) …………………………………them everyday. 14. Dial 113 if you (want) ………………………………… to call the police. 15. I’d take the lift if I (be) ………………………………… the man. 16. Unless we (preserve) ………………… natural resources, the planet will be in danger. 17. If I see him, I (give) ……………………………… him a gift. 18. If I had a typewriter, I (type) …………………………….. the report myself. 19. If he (study) ……………………………….. hard, he can pass the exam. 20. Rice plants (grow) …………………………. well if there is enough rain.

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