Написать предложения в прошлом и будущем времени. Students must make a geat number of experiments to acquire good knowledge.

1. Students must make a great number of experiments to acquire good knowledge. Students had to make a great number of experiments to acquire good knowledge. Students will have to make a great number of experiments to acquire good knowledge. 2. We can remove all the impurities from water by the process called distillation. We were able to remove all the impurities from water by the process called distillation. We will be able to remove all the impurities from water by the process called distillation. 3. You may take the book with you. You were allowed to take the book with you. You will be allowed to take the book with you.