Translate the sentences. Pay attention to the different ways of expressing

Translate the sentences. Pay attention to the different ways of expressing obligation:

1. We must explain the work of this system. 2. One should study hard to be a good specialist. 3. This problem is very complex. You have to think it over properly. 4. We ought to say that this phenomenon is worth investigating. 5. We should be prepared for scientific study of management in industry. 6. Laws must serve people. 7. The lecture is to begin at 6 oclock. We ought to come in time. 8. You were to come to my place yesterday. Why didnt you do that? 9. He will have to improve his knowledge of English.