Переведите последующие предложения, обращая внимание на перевод эквивалентов модальных

Переведите следующие предложения, обращая внимание на перевод эквивалентов модальных глаголов
1. In the extinguishment of a fire the burning substance has to be cooled below its ignition temperature.
2. The officer in charge has to decide whether it is safe to attempt an emergency operation.
3. Gas and air mixtures will be able to burn only within certain limits.
4. At last firemen were allowed to open a building.
5. The chief of the fire brigade has to arrive at work at 6 oclock.
6. All the students are allowed to make experiments in the laboratory.
7. Youll have to do this work again.
8. Our laboratory will be able to launch a new program this month
9. Gas and air mixtures are able to burn only within certain limits.
10. At last firemen were allowed to open up a building.
11. The chief of the fire brigade was to arrive at 6 oclock.
12. A fireman must be able to respond to an alarm during the time in 20 seconds.