plain round nut

例句：

1. 1. The plain clothes she wore were very modest.
   她穿的朴素衣服非常朴素。
2. 2. The plain house had a cozy feel to it.
   这所朴素的房子给人一种温馨的感觉。
3. 3. The plain design of the dress was very elegant.
   这件衣服朴素的设计非常优雅。