20182022英语周报初一答案

34.(1)【答案】ACE(5分)【解题思路】由波动图象可知波源振幅A=5cm,波长A=8m,该波的波速为=4m/,由n=A可得T=2s,)则波源做简谐运动的表达式为y=- Asin ot=-5 sin Tl(cm),A正确;由t=0时刻的波动图象可知x=372m,波源把振动形式传播到质点P所用的时间为1=2=37,所以质点P第次振动到波谷所用的时间为=41+47=1808,B错误;t=7s时质点Q运动到波峰,具有沿y轴负方向的最大加速度,受到的合外力最大,C正确;t=5.4s时,波沿x轴正方向传播的距离s=45.4m=21.6m,传播到x=12m+21.6m=33.6m处,x=33.5m处质点的振动方向沿y轴正方向,D错误;因为t=6s=37,所以t=0到t=6s时间内,质点Q经过的路程为s=3×4A=60cm,E正确。(2)【关键能力】逻辑推理能力【解题思路】(i)作出光路图,如图所示,由几何关系得B1=∠A=30°(1分)由几何关系和反射定律有03=64=90°-261=30°(1分)r=65=90°-∠C=60°(1分)=65-64=30°由折射定律得n=51=3(2分)单色光在AC边发生反射时,因为sin(90°-03)=>sin c=2所以单色光不能从AC边射出(1分)(i)单色光在玻璃工件中的传播速度为=(2分)单色光在玻璃工件中的传播路程为s=DE+2EG=元L(1分)单色光从射入工件到射出工件所用的时间为t=553L(1分)4

第三节One possible versionParagraph 1Finally, afler struggling for a minute or tuo, I still gotpulled underwater. I told myself I should never give upThen I pulled the weed again with great efforts. The weedfinally broke. I swam back to the surface to take a debreath. I saw two young men in canoes, racing each other.I was exhausted and shouted for help. The two men saw meand raced towards me. By the time they reached me, I hadbeen already unconsciousParagraph 2When woke up, I was in an empty room lying on abed. It was not until a doctor came into the room that I realized that I was in a hospital. Jimmy and Bobby told me thetwo young men brought me to the shore and sent me to thehospital. After a few minutes, my parents with half angryand half worried faces walked in. My parents scolded me ifor running out of the house secretly but were also glad thatI was not seriously injured. I will never forget that terrifyingexperience. Neither will I ever want to show off again

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