Write positive and negative sentences, using "must/mustn't". 1. Drivers/drive/on the right-hand side of the road. 2. You/drive/after/you/drink alcohol. 3. Small children/sit/in the front seat of the car. 4. Vehicle/have/seats/for small children. 5. Drivers and passengers of motorcycles/wear helmets. 6. You/drive/at more than 50 km/on this road. 7. You/use/a mobile phone/when you are driving.

1. Drivers must drive on the right-hand side of the road.

2. You mustn't drive after you drink alcohol.

3. Small children mustn't sit in the front seat of the car.

4. Vehicles must have seats for small children.

5. Drivers and passengers of motorcycles must wear helmets.

6. You mustn't drive at more than 50 km/h on this road.

7. You mustn't use a mobile phone when you are driving.

1. Do the engineers carry out the experiments with new building materials?
2. Will the electronic computer make our travel in high speed train safer?
3. Are chemists developing new materials at present?
4. Was the first railway in our country electrified in 1926?
1. The engineers do not carry out the experiments with new building materials
2. The electronic computer will not make our travel in high speed train safer
3. At present chemists are not developing new materials
4. The first railway in our country was not electrified in 1926.

If you ring) me up, I shall tell you a secret. 2. If you were a poet, you would write beautiful poetry. 3. If he did not read so much, he wouldn't know literature so well. (?)4. If he had come to our house yesterday, he would have met his friend. 5. If he doesn't pass his examination, he will not get a scholarship. 6. If she hadn't helped me, I should have been in a very difficult situation. 7. My father would have more free time if he hadn't read) so many newspapers. 8. If only you had let me know, I would have gone there immediately. 9. If I were a famous singer, I would get a lot of flowers every day. 10. If you don't buy coffee, we shall drink tea. 11. If he is free tomorrow, he will certainly come to our party. 12. My brother would not have missed so many lessons if he hadn't hurt his leg. 13. If my friend had worked in my office, we should have met every day. 14. If you spoke English every day, you would improve your language skills. 15.If you get a "five", your mother will be happy. 16.If she had returned earlier, she would have been able to see him before he left. 17. If these shoes were not too big for me, I would buy them