Измените следующие предложения, используя форму времени модального глагола:
1. It must be born in mine that he quickly forgets his promises. 2. Those who cannot read or write have to remember things. 3. We must discuss this problem in detail. 4. A machine can do work which man is unable to do. 5. Every scientist must check the results of his research. 6. The boy tries hard, but he cannon act on the stage. 7. We must do as we are told. 8. The available data is not sufficient, but we must come to a decision.