腰椎间盘突出症最易发病的椎间隙是（）
A.腰2～腰3
B.腰3～腰4
C.腰4～腰5
D.腰5～骶1
E.胸12～腰1
参考答案：C
—How's your weekend, Jack?
—I spent all time _____ my friends. But sometimes I spend time _____ the internet. [ ]
A. on, on
B. in, with
C. with, on
D. on, with
结构性失业是指( )
A．摩擦性失业
B．周期性失业
C．技术性失业
D．季节性失业
