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34.(1)(5分[文]【答案】BDE【解[章]析]由=得F=2H[来]z,A错误:t=0[自]时刻,x=4m处的[知]质点向上振动x=8[嘛]m处的质点向下振动[答],两质点振动方向相[案]反,B正确;波最前[网]端质点起振的方向和[文]波源起振的方向相同[章],则两波源起振方向[来]相反,C错误;两列[自]波叠加后,x=6m[知]处为振动减弱点,C[嘛]正确;x=5m处为[答]振动加强点,在t=[案]0.5s时刻质点第[网]次到达波谷即y=-[文]7cm处,D正确。[章](2)(10分)解[来]析:(1)从C点射[自]出的光线与A点的入[知]射光线平行,其光路[嘛]图如图所示,由几何[答]关系得折射角为r=[案]30①②③④⑤30[网]由折射定律得n解得[文]玻璃的折射率为n=[章]√③B(2)玻璃球[来]的半径为R=5×1[自]0m由几何关系得x[知]=xm=2Rcos[嘛]30°=53×10[答]6m在玻璃中传播的[案]速度为在玻璃中传播[网]的时间为t代入数据[文]解得光束从A点经B[章]点折射到达C点的时[来]间t=1.0×10[自]-13s评分参考:[知]第1问5分,①②式[嘛]各2分,③式1分;[答]第2问5分,④⑤⑥[案]⑦③式各1分
第一节参考范文:L[网]ast Friday evening witnessed[文] a breathtak[章]ing English Singing Contest in our schoolsta[来]dium, where 15 singers competed for"The Best English Singer of the YearThe singers, who had stood out from the first round of selection[自], gave energetic[知]performan[嘛]ces on stage. Throughou[答]t the contest, the atmospher[案]e in the stadium was extremely[网]exciting,[文] with many students singing along to nearly every song. At last, the award went toZhang Xin from Class 1 Grade 1Everyone[章] agreed that the contest enriched our campus life as well as kindling ourpassio[来]n for English learning
