what they share in common,however,is the extraordinary variety of plant and animal life-forms that are a necessary part of the ongoing formation.that指代为什么用are后接a 扫码下载作业帮搜索答疑一搜即得 答案解析 查看更多优质解析 解答一 举报 that是作为定语从句用的,在这里代替或者说等同于which,从句...