---- Have you bought the best-sell book in the store near our school?

-----Yes, I _____ it three days ago,but I hear that they ________

A．have bought, sell out

B．bought, have been sold out

C．bought, have sold out

D．have had, have been sold out

技术的进步造成部分人不适应新的工作要求，由此产生的失业是( )。

A．自愿失业

B．结构性失业

C．需求不足的失业

D．摩擦性失业