WayneCH2012

it 指代this statement,也就是至题目的B选项,第二个it指代converting the Hevelia airstrip to a full-service airpot，意思就是 B选项这个陈述表明一个靠近G机场的未经开发的跑道可能是缓解G机场飞机延误的更好的办法（与在40英里外修建Hevelia跑道相比），但是这个陈述没有告诉我们任何把H跑道转变成全方位服务的机场后的结果.我觉得but后面的句子可能是but it tells us nothing about the effects that converting the Hevelia airstrip to a full-survice airport would have if it were carried out.