如图，小丽在研究斜面机械效率时，用15N的力将重量为25N的物体，沿斜面从底部拉 发布时间：2017-07-23 02:02 │ 来源：www.tikuol.com 题型：填空题 问题： 如图，小丽在研究斜面机械效率时，用15N的力将重量为25N的物体，沿斜面从底部拉到高为10cm的顶端，斜面长为30cm，则她做的有用功是 J。总功是 J，机械效率是 。
题型：填空题 完成对话，从方框中选择适当的句子完成对话，每个句子只能用一次，有两项多余。A. Here you are. B. What do you want to borrow? C. Oh, sorry. D. Can I help you? E. No hurry. F. Never mind. G. My pleasure.(Li Lei arrives at the school library.) Miss Wang: 1 Li Lei: I'd like to borrow a book on electric (电的) head.Miss Wang: "Electric head?" I've never heard of it. Maybe … Li Lei: 2 It should be "a book on computer."Miss Wang: I see. Yes, there is still one on the shelf. 3 Li Lei: Thanks a lot. Miss Wang: 4 Li Lei: I'll try to finish it as soon as possible. Miss Wang: 5 You may keep it for two weeks. 1.____ 2._____ 3._____ 4._____ 5._____ 查看答案
题型：填空题 直接写出得数．2.4×5=178.5-36.5-63.5=250×0.02=7.86×99+7.86=0.72×16=25×37×25×712=17×2÷17×2=56÷512= 查看答案
