2022学英语周报，八年级上册，第二期答案

18.解:(1)证明:因为面ABCD⊥面ABEF,AF⊥AB,面ABCD∩面ABEF=AB,AFC面ABEF,所以AF⊥面ABCD2分因为BCC面ABCD,所以BC⊥AF,……连AC,在梯形ABCD中,由AB=2,AD=1,CD=1AD⊥AB,有∠DCA=∠BAC=45°,∠CBA=45°,∴BC⊥ACBC⊥AC,BC⊥AF,AC,AFC平面AFC,AC∩AF=AC⊥平面AFC6分CFC平面AFC,∴BC⊥FC(2)分别以AB,AF,AD所在直线为x,y,z轴,建立空间直角坐标系,则B(2,0,0),C(1,0,1),F(0,2,0)E(2,1,0)8分EF所以BC1,0,1)设平面BEC的法向量为m=(x,y,z),平面BEC与直线EF所成的角为0BE1,则0,1),取BCm. EF所以12分故直线EF与平面BEC所成角的正弦值为0

【语篇导读】本文是夹叙夹议文,告诉我们“远兼如近邻”的道理。5.A【解析】细节理解题。根据第一段 Much morerobably it is a close female friend calling to tell you thatshe has split up with her boyfriend again or perhaps'simply that a good movie has just started on TV,可知最有可能来自一个朋友,故选A。6C【解析】细节理解题。根据第三段 TV shows likethis tell us that our romantic relationships may not lastbut we need to keep in touch with out close friends, ifwant to survive可知 TV shows like Friend告诉我们亲密的朋友帮助我们面对生活中的困难。故选C。7D【解析】推理判断题。根据最后一段 This is trueof Erika and Jane's friendship. With Erikas family 200miles away, it is Jane who keeps a spare set of keys toErika's apartment and waters her plants whenever she isaway.可知Enka和Jane在日常生活中互相信任和支持。故选D。8A【解析】推理判断题。纵观全文,特别是最后一E My friends have more to do with my life than my par-ents and, therefore, 1. don t have to spend a lot of timeexplaining things to them. Friends are more up to datewith what is happening.可知远亲不如近邻。故选A。

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