目前已经上市的关于中国概念的股指期货有______。

A．美国芝加哥期权交易所的中国股指期货

B．NSDAQ中国企业指数期货

C．新加坡新华富时中国50指数期货

D．中国香港以恒生中国企业指数为标的的期货合约

A boy walking along a road at 3 kilometers per hour is overtaken by 3 truck traveling at 40 kilometers per hour. If the truck breaks down 1 kilometer beyond where it passes the boy, how many minutes after the breakdown does the boy reach the truck ？（）

A.A

B.B

C.C

D.D

E.E