2018-2022英语周报他答案

11.参考答案BCD说明分析对于A,当P与点D1重合时,PQ⊥EF,故选项A错误对于B,由于点P是棱CD1上的动点,EF是棱AB上的一条线段,所以平面PEF即平面ABCD建立如图所示的空间直角坐标系,则Q(2,0,4),A(4,0,0),B(4,4,0)所以QA=(2,0,-4),AB=(0,4,0),平面QEF即平面QAB设平面(QAB的法向量为n=(,y:1.则/moi=a0,令z=1,得平面QAB的一个法向量为n=(2,0,1)第11题图同理可求得平面ABCD1的一个法向量为m=(1,0,1设二面角P-EF-Q的大小为3√0所以os=|cos(m,n)|=√0故选项B正确对于C由于AB⊥平面BBC,又BCC平面BBCC所以AB⊥BC1,所以BC⊥EF,所以BC是△PEF的高所以S=1·EF·BC1=1x1×42=22,故选项C正确对于D,由于CD1∥EF,且CD￠平面QEF,EFC平面QEF,所以CD1∥平面QEE又点P在CD1上,所以点P到平面QEF的距离为定值,故选项D正确.故选BCD

书面表达One possible version:NOTICEA sports meeting will be held in the playground of our school from next Thursday to FridayAs you know, the pressure of study is very heavy now, especially for those senior 3. So the purpose of the sports meeting is to letevery student get relaxed, as a result of which we students can live happily and heal thilyEveryone is welcome to take part in it. Those who perform excellently at the sports meeting will get prizes. But don' t take theresults so serously because taking part is more important than the result. Good luck to everyone!

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