A:乙烯和乙炔
B:苯和正己烷
C:苯和甲苯
D:甲苯和1—己炔
已知两角及夹边作三角形,所用的基本作图方法是( )
His parents were worried that he______ too much time chatting on line.
下列数据3,2,3,4,5,2,2的中位数是( )