关于股票指数期货交易，正确的是 ( )
A．交易对象是股票
B．交割时用股票履约
C．不可用于套期保值
D．是一种没有股票的股票交易
参考答案：D
Although there were only five athletes ____ in the race, it was a rather exciting one.
[ ]
A. competing
B. having been competed
C. to compete
D. to be competed
钻机工风险预控措施有（）
A.审帮问顶、安全确认
B.重物上方严禁站人
C.远离钻机转动部位
D.打牢打齐戗压点柱，拴牢柱头
E.携带便携式瓦检仪，保持常开状态，报警立即撤人至安全地点
