The reason why the earth is different from other planets______(go) around the sun is that waterbegan to appear on its surface after the earth cooled down.这空填什么形式?为什么?
问题描述：
The reason why the earth is different from other planets______(go) around the sun is that water
began to appear on its surface after the earth cooled down.这空填什么形式?为什么?
答