为了培养学生勇于承担社会责任，学做负责的公民，某校有计划地开展了一系列教育活动。活动之一是设立“校园文明窗”，供全校学生应聘。具体岗位及要求见下表：

分析材料，完成问题： 

如图（a）所示，“ ”型木块放在光滑水平地面上，木块的水平表面AB粗糙，与水平面夹角θ＝37°的表面BC光滑。木块右侧与竖直墙壁之间连接着一个力传感器，当力传感器受压时，其示数为正值；当力传感器被拉时，其示数为负值。一个可视为质点的滑块从C点由静止开始下滑，运动过程中，传感器记录到的力和时间的关系如图（b）所示。（已知sin37°＝0.6，cos37°＝0.8，取g＝10m/s²。）求：

人的体细胞中共有____对染色体，其中性染色体有____对．

                                                                                         How to Become Fit?
   Healthy eating habit along with regular exercise is the only way to become fit. If you have the correct number of calories and exercise regularly, you will lose weight, keep fit, and feel great, too.
   During your teenage years, it is important to give your body the energy it needs. If you skip (跳过) meals, you won’t get enough calories, and then you will feel tired. By the way, calorie is just another word for energy. About 50% of your calories should come from rice, bread, vegetables and fruit. You also need to drink a lot of water, 6 to 8 glasses a day. Water helps keep your system clean. Drinking enough water will make your skin better and make you healthy.
   Exercise is something that can help to make you look good, feel good and be healthy. Experts suggest that teenagers spend at least 30 minutes exercising, five times a week. That is easy to do! You can walk or ride your bike to school, and do sports at school. However, teenagers often give up sports, saying they have no time left after their studies. In fact, doing exercise can help them sleep better at night and increase their ability to focus on their study.
   If you follow the suggestions above, you will look and feel much better and become fit.