demonstrator

例句：

1. 1. The teacher demonstrated the new technique to the students.
   老师向学生演示了新技术。
2. 2. The scientist is a demonstrator of his research findings.
   这位科学家是其研究成果的示范者。
3. 3. The engineer demonstrated how to fix the car's engine.
   工程师演示了如何修理汽车发动机。