2022八年级上册英语周报新目标答案。

21.ABD由牛顿第二定律得F-mg=ma,pmg=Ma2,解得a1=2m/s2,a2=1m/s2,力F撤去时小物块和长木板的速度分别为v1=a1t=6m/s,w=a2t=3m/s,选项A正确;最后二者共同匀速,由动量守恒定律mv+Mv=(M+m)v解得v=4m/s,对小物块全过程应用动量定理得Ft-pmgt'=mv-0,解得t=4s,选项B正确;小物块在力F作用下发生的位移大小为x1=t=9m,力F做的功为W=Fx1=36J,选项C错误;由能量守恒得W=Q+(M+m)v2,解得Q=12J,选项D正确.

语篇类型:说明文主题语境:人与社会——体育—竞走运动及其与跑步的不同之处文章大意:本文主要介绍了竞走这项运动的相关情况及其与跑步的不同处28.c【命题意图】考查细节理解。【答案分析】由题干中的关键词 conditioned athletes可将解题信息定位至第二段,根据该段中的" But the sports rules require that a race walkersknees stay straight through most of the leg swing and one foot remain incontact(接触) with the ground at all times"可知,竞走运动的规则要求竞走者的膝关节在腿摆动时的大部分时间里伸直,同时一只脚保持与地面接触。据此可知,竞走者必须遵循一些特殊的运动规则,故C项正确29.D【命题意图】考查推理判断【答案分析】根据第五段中的" some of the injuries associated with runningsuch as runner's knee, are uncommon among race walkers"可知,一些与跑步有关的损伤,如跑步者的膝盖(受伤),在竞走者中并不常见。据此可知,竞走不太可能导致膝盖受伤,故D项正确30.A【命题意图】考查细节理解【答案分析】根据第五段中的" anyone wishing to try race walking shouldprobably first consult a coach or experienced racer to lean proper technique可知, norberg博士建议任何希望尝试竞走的人或许应该首先咨询下教练或有经验的竞走者,以学习正确的技巧,故A项正确31.B【命题意图】考查观点态度【答案分析】根据全文内容可知,作者提到了竞走这项运动的好处,同时也指出它的一些危害,态度是客观的,故B项正确。M======二次精读--【词汇积累】Para.l: fitness n.健康Para.3: demanding ad.(工作)要求高的,费力的;(人)苛求的,难满足的 calculation n.计算;估计 approximatelyad.大约Para.5: considerable ady.相当大的;相当多的 cautious ady.谨慎的,小心的【难句分析】 According to most calculations, race walkers moving at a pace of sixmiles per hour would burn about80 calories(卡路里) per hour,, which isapproximately twice as many as they would burn walking, although fewer thanrunning, which would probably burn about 1, 000 or more calories per hour分析:本句是一个主从复合句,含有两个 which引导的非限制性定语从句,第一个 which引导的定语从句修饰800 calories,第二个 which对 running进行补充说明。译文:根据大多数计算,以每小时六英里的速度移动的竞走者每小时会消耗大约800卡路里,这大约是他们走路燃烧的两倍,虽然它比跑步消耗的卡路里少,跑步可能每小时消耗1000左右或更多的卡路里。

以上就是2022八年级上册英语周报新目标答案。，更多英语周报答案请关注本网站。