问题描述：
请问为什么要用having been separated?而不是用to be separated?
Having been separated from other countinents for millions of years,Australia has many plants and animals not found in any other country in the world.
Having been separated from other countinents for millions of years,Australia has many plants and animals not found in any other country in the world.
问题解答：
我来补答展开全文阅读