题目

Some people say that the best way to reduce the size of your waist is to do stomach exercise. Many people believe that when specific muscles are exercised, the fatty tissues (组织) in the immediate area are burned up. The truth is that exercise burns fat from all over the body and not from one specific area. Of course, if you reduce the fat throughout your body, you will certainly see results around your waist too.Some people believe that you need to exercise twice a week in order to keep a sufficient level of physical fitness. However, studies directed by American scientists show th 如图所示是研究电磁现象的四个实验装置，其中奥斯特实验装置是 [　　] A． B． C． D．