英语周报外研八年级2021-2022学期答案

15.2【解析】本题考查线面角的问题,考查空间想象能力和运算求解能力如图,取AC的中点O,连接PO,BO因为AB⊥BC,所以OB=OA=OC.又PA=PCPB所以PO⊥AC,可证△PAO≌△PCO≌△PBO,所以PO⊥OB,从而PO⊥平面AcBO21ABC,所以PB与平面ABC所成角为∠PBO,cos∠PBC=BPBP=2

【参考范文】The little boy headed back down to the old man's house. The thought of knocking at the oldman's door filled the little boy with fear, but he still knocked on the door, waiting breathlesslyFinally, it opened, and out came the old man. Seeing the boy holding a well-wrapped dog figurinehe looked very astonished but still glared at him without a word Determined to break the ice. theboy gave the old man the gift with a precious card attached, expressing sincerely caring about himDeeply moved by all the boy did, the old man could say nothing but to hug him tightly, with tears ofappreciation welling up. Out of gratitude, he bought a magazine from the boyFrom that day on something changed inside the old man. He adopted a real live dog and treatedhim as his child. It seemed that it was the company of the dog that led the lonely soul out ofdarkness and loneliness. Gradually, he was willing to greet others with a bright smile, expressinghis appreciation to life. Indeed, only when we open up the door of our heart can we be bathed inthe brilliant sunshine and enjoy the warmth of love and care

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