be at the bottom of

• vi. 是 ... 的根本原因

例句

用作不及物动词 (vi.)

1. The next Accretionary Wedge is being hosted at The Office of Redundancy Office.
   闻丞说，迁徙，是由很多因素控制的，其根本原因是为了寻找更合适的生存环境。