题目

一段通电导体处于磁感应强度为B的磁场中，导体电流为I，长度为L，当导体垂直磁场放置时，安培力F=__________；平行磁场放置时，安培力F=__________. 答案：BIL   0阅读短文，回答问题。 Stress occurs all the time in most people’s lives. Too much stress, however, can seriously affect physical and mental well-being. Stress decreases the quality of life by reducing feelings of pleasure and accomplishment. At some point in their lives, almost all people will go through stressful events or situations that limit their ability to cope. Financial concerns are one of the main stressors for a man. He is supposed to be able to “support” his family. In today’s economy, a family living on a single income is rare. Most often the woman is working outside the home also. Job-related stress may increase the risk of heart disease. It appears to have a greater effect on a man’s arteries(动脉) than on a woman’s. Men who report the most stress have almost five times the risk of having more serious artery disease. One temporary treatment for job stress may be stress-reduction exercises. Sometimes these techniques can be quite easy and simple. Taking a few minutes to practice relaxation or meditation can help to ease some of the stress. Taking a vacation, developing interests outside of work, and finding supportive friends who will listen can help to relieve stress. Sometimes, changes in the workplace or renegotiation of the demands of the job may be needed. This may require joining with other workers to document stress conditions. More and more marriages are ending in divorce now. It is not uncommon for a man to find that he is the primary caregiver for his children, or that he has joint custody(联名保管(户)). This may involve a lot of changes for him. It can be very stressful until a routine is formed. This is especially true for a man who has not been able to be involved much in raising his children because of his job. There are support groups that a man can join to help him deal with these changes. Changes a man goes through in middle age may increase stress. If he is not active, he may gain weight. Staying active, eating a healthy diet, and getting plenty of sleep will help to decrease the stress. In addition, exercising and talking to someone can also help to relieve the stress. Getting rid of stress from life is impossible. However, stress management techniques can decrease some of the harmful effects of stress. 1. Almost all people are affected by stress sometimes in their life because __________. A. they are lacking in the stress management techniques B. they will unavoidably come across things beyond their ability C. they are too busy working to do physical exercises D. they are so selfish that they think family is a burden 2. If a man feels stressful, he can try the following means EXCEPT ________. A. having a chat with friends B. doing some physical exercises C. changing the workplace D. working harder to make more money 3. According to the passage, a middle-aged man may feel even more stressful when he __________. A. finds that his wife still has to work B. notices that his weight remains the same C. realizes that he doesn’t have to change his job D. deals with a lot of changes negatively. 4. Judging from the context, the underlined word “ease” most probably means __________. A. making more comfortable               B. making less difficult C. making less serious                         D. making less complicated 5. From the passage we can infer that __________. A. it’s dangerous for a man to be under stress from work for a long time B. it’s likely for a man to be free from stress if he lives a healthy life C. it’s very stressful for a working man to share the care of children with his wife D. it’s common for a man to be the only wage-earner in a family nowadays