----How did he finish the work?----I hear that he did it __________.
A:in the own
B:on his own
C:of the own
D:all his own
“一堆沙子是松散的,可是它和水泥、石子、水混合以后,比花岗岩还坚硬。”这句话让我们从中领悟的道理是( )
两直线3x+y﹣3=0与6x+my+1=0平行,则它们之间的距离为( )