题目

词语填空 （共10小题，计10分）用方框中所给单词的适当形式填空，使短文通顺、正确、连贯（每个单词限用一次）。that  happy  healthy  fun  exercise  fly  hard  swim  listen  manyThe summer vacation is over. It’s true that time always   【小题1】 fast. During the vacation, the weather was hot and I could not do much work, but I lived   【小题2】. As the afternoon was hot. I did my work in the morning. I used to get up at 6:30 and take a walk in the garden for half an hour. After breakfast, I began reading English and Chinese and如图所示，滑轮组提起重630N的货物，绳子的自由端拉力F=300N，重物以0.2m/s的速度匀速上升，不考虑绳重和摩擦，求：（1）此时滑轮组的机械效率（2）拉力做功功率（3）当所提货物重力为930N时，绳端的拉力为多大？此时滑轮组的机械效率是多大？