题目

It’s just pipes, water and pumps, but we haven’t heard of anyone else ________ this technology in this way before. A. to use B. using             C. use              D. used 答案：B1.    anyone else using this technology in this way为动名词的复合结构，做haven’t heard of 的宾语。  脊椎动物中种类最多的类群是（　　）A．鱼B．爬行动物C．鸟D．哺乳动物