11. But I have to get serious. And how do you get serious? 12. His look was very serious , like some one lost far away . 13. And he laughed again . Then he quickly became serious : 14. These can be serious or even fatal diseases . 15. This will help to protect them from serious injury . 16. This will help to protect them from serious injury. 17. They all are major causes of serious illness or early death; 18. This will help to protect them from serious injury . 19. This was most unsatisfactory for carrying on any serious study . 20. Given that, even though it's a very serious cause,
