在废弃的池塘中长出树林，大约是经历以下几个阶段：①干涸池塘阶段；②灌木阶段；③乔木阶段；④草本植物阶段。演替的正确顺序是 ( )
A：①→②→③→④
B：②→③→④→①
C：①→②→④→③
D：①→④→②→③
—Listen! Marry is singing in the next room.
— It be Marry. She has gone home.
--Three times．
导线中的电流是10﹣8A，导线的横截面积为1mm2．
