半坡类型彩陶

等差数列{an}中,a1=1,d=1,则Sn等于? 设圆上的点A(2,——3）关于直线X+2Y=0的对称点仍在这个圆上,且与直线X-Y+1=0相 已知A是圆C:(x-a)^2+(y+2)^2=a^2+10上任意一点,且点A关于直线l:x+2y+1=0的对称点也在圆上,求a的值 已知圆C:x^2+y^2+DX+EY-1=0,圆C上一点A（4,1）关于直线x+2y-2=0的对称点仍在圆上,且点A也在椭圆E：X^2/a^2+Y^2/b^2=1(a>b>0)上.（1）求圆C标准方程. 因式分解：-7a^2+21a=-7a（ ） 在△ABC中,有a/sinA=b/sinB=c/sinC,请画出一个锐角三角形并证明 ( )The shop_________early in the morning a.open b .opens c.is open d. opened The shop _____ at seven.A.opens B.open C.is opening D.is opened 3、x4十7x2一8.4、a4一a3十a2一a.5.(ax十by)2十(bx一ay)2因式分解 因式分解3、x4十7x2一8.4、a4一a3十a2一a.5.(ax十by)2十(bx一ay)2 锐角三角形ABC中的内角A The bookshop____(opens/is open).It usually____(opens/open/is open)at eight in the morning the shop ____(open) at 8:00 a.m.and it ____(open)for ten hours every day.用正确形式填空 The shop _______ (open)at 6a.m.every day填什么?为什么? 3a^3-12a^2+12a-9-6ab-a^2b^2(a+2b)^2+2(a+2b)(2a+b)+(2a+b)^2 (12a^3-12a^2+3a)/3a 3a-12a^2+18a^3因试分解 3a^3-6a^2+12a 计算：(12a^3-3a)÷(3a)-(2a)^2 因式分解8+7a-a^2 The shop__at 8;00a.m.,and it__for ten hours every day.(填open的形式）并解释 the shop ____(open) at 8:00 a.m.and it ____(open)for ten hours every day.第一个空为何不能用被动 The shop ___at8:00 and .it ___for ten hours every day.A .opens is open.B .is opened .opensC .is open ,has openedD opened,opens Mr wilson goes to work by bus every day.改为同义句 Mr wilson ____ ____ ____ ____work every day.4个 He goes to work by bike every day同义句谢谢,,求多种方案 He goes to work by bus every day否定句和一般疑问句 He goes to work by bike every day.同义转换He ___ ___ ____ to work every day.He goes to work ____ ____ ____ every day. He goes to work by car every day.同义句 shop (opens) at 8:00 am and it (is opened) for ten hours every day括号里的为什么要这么填? 如图在△abc中,∠bac=90°,ad⊥bc,垂足为点d,ce平分∠acb,交ad于点g交ab于点e,ef⊥bc垂足为f求证四边形aefg是菱形. 几道英语题求解释,谢谢When＿the hospital＿?A.did；build B.is；built C.does；build D.was；builtHow long＿the supermarket＿?Four years. A.has；opened B.has；been opened. C.did；open D.has；been openMy glasses are broken.I will bu 1.they use computers to keep the traffic ( )smoothly.A being run B run C to run D running为什么不用动词过去分词B呢?而用D呢?2.frequently do something which touches people's hearts.and also allow yourself () by the kindness of others.A t