The city has an open-door policy for immigrants from all over the world.

open-door 是由形容词 open（开放的）和名词 door（门）组成的复合形容词，字面意思是"敞开的门"，引申为"开放、欢迎"的意思。 open-door policy 指"开放政策"，表示对特定群体（如移民）采取欢迎和接纳的态度。