问题
填空题
图是提取式抽水机示意图，AB为一轻质杠杆，O为支点，动力臂为0.6m，阻力臂为0.2m，这是一个_________（选填“省力”或“费力”）杠杆。若作用在B点的阻力为60N．则在A点至少需加_________N的力。
答案
省力 20
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图是提取式抽水机示意图，AB为一轻质杠杆，O为支点，动力臂为0.6m，阻力臂为0.2m，这是一个_________（选填“省力”或“费力”）杠杆。若作用在B点的阻力为60N．则在A点至少需加_________N的力。
省力 20
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| Hello, everyone. Here is something important for everyone going to London next month. As you know, you are going to stay with a family for two weeks. Now, the most important thing is money. You should take about $530 with you. I think it will be enough for everyone. Then, when you arrive, your new family will meet you. You must remember to wear a red shirt, so the family will find you easily. They've been told you all wear red shirts. You'll also need to take with you 4 photos of yourself and, of course, it's very important that you take the school letter. While you're there, if you have any problems, you can call Leech School Office. I'll give you the office phone number now: it's 580-4436 and the person to ask for is Mrs Belcher…She's in the office from nine o'clock in the morning until five in the afternoon every day. OK. That's everything. Have a good journey! | ||||||||||
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