外层 outer layer
exothecium
outer shell
outer skin
surrounding
- 那两个航天舱在外层空间对接。
The two modules docked in outer space. - 他是第一位研究外层空间的科学家。
He is the first scientist studying outer space. - 压缩气体从风扇腔体的最外层流出。
The compressed air flows out radially from the outer diameter of the fan housing.