within four walls

• 在室内

within four walls的用法和样例：

例句

1. Fix the protectors on the indoor walls or windows.
   将保护器固定在室内的墙壁上。
2. The excitement of watching races within the stadium for ticketholders can happen outside as well through the Velo-Fountain.
   在室内自行车场内看比赛的兴奋，在喷泉这儿，我们同样感受得到。