to be lost in thought

• 陷入沉思

to be lost in thought的用法和样例：

例句

1. My sister sat silent for some time,lost in thought.
   我姐姐沉默地坐了一会儿，陷入沉思。
2. She was lost in reflection on her future.
   她为自己的未来而陷入沉思之中。