It is no secret among athletes that in order to improve performance you’ve got to work hard.
　　However, hard training breaks you down and makes you weaker, it is rest that makes you stronger.
　　Improvement only occurs during the rest period following hard training. This adaptation is accomplished by improving efficiency of the heart and certain systems within the muscle cells.
　　During recovery periods these systems build to greater levels to compensate for the stress that you have applied. The result is that you are now at a higher level of performance.
　　If sufficient rest is not included in a training program, imbalance between excess training and inadequate rest will occur, and performance will decline. The “overtraining syndrome (综合症)” is the name given to the collection of emotional, behavioral, and physical symptoms due to overtraining that has persisted for weeks to months. It is marked by cumulative exhaustion that persists even after recovery periods.
　　The most common symptom is fatigue. This may limit workouts and may be present at rest. The athletes may also become moody, easily imitated, have altered sleep patterns, become depressed, or lose the competitive desire and enthusiasm for the sport. Some will report decreased appetite and weight loss. Physical symptoms include persistent muscular soreness, increased frequency of viral (病毒性的) illnesses, and increased incidence of injuries.
　　The treatment for the overtraining syndrome is rest. The longer the overtraining has occurred, the more rest required, therefore, early detection is very important. If the overtraining has only occurred for a short period of time (e.g. 3-4 weeks) then interrupting training for 3-5 days is usually sufficient rest. It is important that the factors that lead to overtraining be identified and corrected. Otherwise, the overtraining syndrome is likely to recur. The overtraining syndrome should be considered in any athlete who manifests symptoms of prolonged fatigue and whose performance has leveled off or decreased. It is important to exclude any underlying illness that may be responsible for the fatigue.

某校中学生准备编辑一期墙报，主题是“自觉维护民族团结”。下列选项符合这一主题的有（　　）
①各民族同学互相帮助，共同进步
②了解和尊重少数民族风俗习惯
③公民要履行维护民族团结的义务
④同破坏民族团结的行为作斗争

一个用于防震的L形包装塑料泡沫如图所示，则该物体的俯视图是（　　）

大蚂蚁和小蚂蚁生活在某地相邻的两个区域，研究者在这两个蚂蚁种群生活区域的接触地带设4种处理区。各处理区均设7个10m×10m的观测点，每个观测点设有均匀分布的25处小蚂蚁诱饵投放点。在开始实验后的第1天和第85天时分别统计诱饵上小蚂蚁的出现率进行比较，结果见表。

处理区		小蚂蚁出现率的变化（﹪）
定时灌溉	不驱走大蚂蚁	增加35
	驱走大蚂蚁	增加70
不灌溉	不驱走大蚂蚁	减少10
	驱走大蚂蚁	减少2

一质量为，半径为，高的圆柱体，可绕轴线转动，在圆柱侧面上开有一与水平成角的螺旋槽，放一质量也为的小球于槽中，开始时小球由静止从圆柱顶端受重力作用滑下，圆柱体同时发生转动。设各摩擦均不计，试求当小球滑落到圆柱体底部时，小球相对圆柱体的速度和圆柱体的角速度。