七年级上册英语周报新目标第20期答案

23.(1)ABC(2分)(2)2.8(2分)(3)2(分)1(2分)(2分)电因打点计时器纸带运动时款由,是小,位追用电太花打点计时器误差小,故A正确;行子商力的操作时,需要提前取下盘及其中砝码的总重力代替,所以雷要托盘及其中砝码的总质量远小于小车的质量,D误,故本题选ABC(2)根据△r=a下运用逐差法得,=二型12.45+925-6.60-4.05)×1020.012.8ms(3)设小车的质量为M则有F=(M+m)a变形得,11m+1M,所以做以小车中砝码的质量m为横坐标,为。纵坐标图线,L一m图象的斜率为一F,所以小车受到的拉力F=·图象的截距,F=b解得小车的质盘:M

书面表达Dear Sir or MadamI am Li Hus, an exchenge student from China. Wanting to get a library card in your library.(背景2分)1 am writing to ask for some relvant information.(目的3分)to begin with, could you please tell me what kind of books can beborrowed?(要点一6分) besides, I would be very interested to ksomething about borrowing system, including how long I can keep thebooks, how many books I can borrow once, and how much I should pay(要点二6分)L8 t but not least, I also wonder when and where I canmake it.(要点三6分)a中aThanks for your ime and I would appreciate it if you can give an earlreply.(表感谢+期回复2分)1量里的0+Yoour sincere.yLi H点国惊口人国文

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