Leadin
n. 引入线；用以引起兴趣的事物；导言\\na. 引入的
🗣️ 情景例句
So, you're an exchange student.
哦，你是一名交换学生。
Knowledge advances by steps and not by leaps.
知识只能循序渐进，不能跃进。
You'd better take a hat.
你最好戴上帽子。