2021-2022 英语周报 八年级 HNN 14答案

21(香暴⑨BC考什么Q命题人考查带电粒子在有界磁场中的运动和核反应方程旨在考查考生的分析综合能力。这么考Q氦核的质量大于氘核的质量,二者动量大小相等,根据P=m可知,射出的粒子速度满足t<,A项错误;若氦核由H与H聚变产生,根据质量数和电荷数守恒可知,核反应方程为H+{H|→He+an,B项正确;根据左手定则可知氮核和氘核在磁场中做匀速圆周运动的向心力由洛仑兹力提供,故有qB=m一,可得由此可知,从M、N两点离开的粒子做匀速圆周运动的半径比为2:1,结合几何知识可知NP=2MP,C项正确;氦核和氘核的比荷相同,由T=2m=2m可知,一二者在磁场中运动的周期相同,由于二者在磁场中运动的偏转角度相等,则二者在磁场中运动的时间相等,D项错误。

书面表达One possible version:Dear PeterI'm writing to invite you to attend a lecture about exercise and health in our schoolAs you know, there are many students who are overweight or short-sighted in our school. They devote all their energy to studying andignore exercise. As a result, they are not so strong and healthy as they should be. Besides, some girls choose to keep slim by controlling thdiet, which also affects their health. So we hope to promote some health knowledge through this lecture: The lecture, which is to be held in theschool hall next Friday afternoon, will last from 3: 00 pm to 5: 00 pm. I hope you can attend it and share something with us.ooking forward to receiving your early replyYours sincerely

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