题目

任务型阅读A. A general sleep rule.B. The importance of sleep.C. A funny sleeping example.D. Different levels of sleep.E. The time we need for sleep.F. Different states of sleep. Sleep, as we know, is important to us because it helps restore tired organs and tissues in our body. But how much sleep do we actually need? For most of us, eight hours seems to be about the right amount. Yet we know that there are a great many people who get along perfectly with less sleep and some who may even need more. A great deal depends on the way we live. But a good general rule to follow is to sleep as lo在“探究杠杆平衡条件”的实验中：（1）把杠杆挂在支架上，没挂钩码时，发现杠杆右端下倾，可以将右端螺母向______（选填“左”或“右”）端旋转，是杠杆在水平位置平衡．（2）实验中共有6个相同的钩码，杠杆上每个距离相等，如果已经挂有3个钩码，如图所示，为了使杠杆在水平位置平衡，在图上画出你挂钩码的数量和位置．