无表情的

例句：

1. 1. The detective was expressionless as he listened to the story.
   侦探听故事时面无表情。
2. 2. The scientist's face was expressionless when he spoke.
   科学家说话时面无表情。
3. 3. She wore an expressionless mask during the presentation.
   在演讲中，她戴着一副毫无表情的面具。