- layer upon layer; ring upon ring
- ♦ ~包围 surround ring upon ring
- ♦ ~设防 set up successive lines of defence; erect defensive works in depth
- ♦ ~把关 check at each level
| 词汇 | 层层 |
| 释义 |
|
| 随便看 |
|
sap英语在线翻译词典收录了95854条英语词汇在线翻译词条，基本涵盖了全部常用英语词汇的中英文双语翻译及用法，是英语学习的有利工具。