— Everyone should learn to say "I love you" to their parents often.
— I think so. _____ in life is more important than family.
A:Something
B:Everything
C:Anything
D:Nothing
如图,在平面直角坐标系中,线段OA与线段OA′关于直线l:y=x对称.已知点A的坐标为(2,1),则点A′的坐标为____
物体在做匀速直线运动,由公式v=s/t,可知( )
装满氧气的集气瓶,按下图所示,用带火星的木条分别甲.乙两种方式迅速插入,发现木条复燃,且在甲中燃烧比在乙中更旺.上述实验说明了氧气具有的性质是:
①____,②____.