20229北师大版英语周报43期答案

第二节One possible version:I recalled the lad s words. I thought it was time to pay her kindness forward, by buying the twomen a meal and two cups of coffee to thank them for all that they had done. So I paid the bill and wrotedown my blessings as well as"paying it forward"on the back of the bill. The firefighters were confused atfirst, but upon listening to me explaining everything, they accepted my offer pleasantly. After their mealthey left gratefully and joyfullOne of the firefighters posted the picture of the bill online and explained his ex perience in therestaurant. The post has since gained the attention of social media users all over the world, receivingcountless shares and likes in less than three days. Many people shared their stories in the comment sectionabout how they "pay it forward"and a lot more people decided to follow my example to do the goodpractice just as we did. viewing those heartfelt comments, I realized that by helping others, we can starta chain of reaction of positive feeling and good deeds that can benefit our whole society.

12:BC【解析】由Ⅰ-U图象可知,图象的斜率为灯泡L的电阻的倒数,所以灯泡L的电阻随电流的增大而增大,故A项错误;由图象可知,灯泡L的电压U=9V时,电流I=1.5A,所以灯泡L的额定功率为P=UI=9×1.5W=13.5W,故B项正确;当R=109时,电路中电流最小,灯泡L消耗的电功率最小,如图所示:A15F-x1.00.546810UV可得此时灯泡L的电流I=1.0A,电压U=2V,所以灯泡L的功率P=UT=2×1W=2W,故C项正确;因灯泡L的额定电流为I=1.5,正常工作时的电阻R1==9=69,根据闭合电路欧1.5t姆定律有I=R+R可得R=7°、12EE6)Q=29,即滑动变阻器接入电路的电阻至少为2a;放D项错误。

以上就是20229北师大版英语周报43期答案，更多英语周报答案请关注本网站。