题目

Having introduced the new equipment, our factory turned out in 2004 as the year before. A . cars three times as many as B . three times as many cars C . as many cars as three rimes D . three times more cars than 答案：B下列各项中，不能看作一个生态系统的是（ ）A．一块农田B．一条河流C．一个池塘里的全部鱼D．一片草原