A、Going to bed earlier. B、Working much harder. C、Reading more books. D、Knowing how to relax. D事实细节题。短文后半部分介绍了缓解压力的途径，包括学会放松、轻缓顺畅

Stress is a very normal part of life. Most people feel stress at some time in their lives. It doesn’t come from an event itself, that is, from the things that are happening in our lives. It comes from the meaning we give to what has happened. We can experience stress any time we don’t feel we have control. It is the body’s way of showing anxiety or worry. Stress is not just caused by our mental or emotional condition, it is also influenced by how tired we are, whether we have a balanced diet with enough vitamins and minerals, whether we get enough physical exercise, and whether we can relax. If we feel stressed, there are several things that we can do. First, we need to learn how to relax and breathe slowly and smoothly. We can also take some time out of our worried, busy schedule to notice the small things in life. Smell the air, look at the flowers, and notice the small designs in the leaves on a tree. These activities can do much to quiet us and to give ourselves a small break in a busy schedule. We need to take care of our bodies. Being tired makes it easier for us to get sick and to develop physical problems related to stress. We need to get enough rest, eat well, and do some regular exercise. Finally, we need to find out what is causing the stress in our lives. Once we have found it, we need to begin to change that part of our lives. If we believe that we can control stress, we can begin to control our lives.
19. Which of the following causes stress according to the speaker?
20. What can help us get rid of stress?
21. How can we start to control our lives?