下列剪纸图案中,属于中心对称图形的是( ) A. B. C. D.
如图所示,在跟匀强磁场垂直的平面内放置一个折成锐角的裸导线MON,∠MON=α。在它上面搁置另一根与ON垂直的导线PQ,PQ紧贴MO,ON并以平行于ON的速度V
________not to drive after drinking, some drivers are still trying their luck, which is really dangerous. A.Being reminded B.To remind C.Having reminded D.Reminded
圆周上有6个等分圆周的点,从这6个点中任取3点构成三角形,求所取三角形为直角三角形的概率.
阅读材料: 英国人一定是丧失了所有的道德和自由感,否则怎么会对这场世界经历过的最重要革命,对它正在进行的庄严方式,不表敬仰赞赏。凡有幸
---- Here. Your new computer is ready. ----Thank you. ---- _______to call this number if you have any problems or questions. A. You are free B.It is free C. Feel free D.Don’t forget
已知ax2yb﹣bxay5=cx2y5,且无论x,y取何值该等式恒成立,则c的值等于__________.
下列各溶液中,微粒的物质的量浓度关系正确的是 A.0.1 mol/L Na2CO3溶液:c(OH-)=c(HCO3-)+c(H+)+2c(H2CO3) B.0.1 mol/L NH4Cl溶液:c(NH4+ )=c(Cl-) C.