此处over 表“在...期间”"在...过程中”
如 My grandchildren will stay over Christmas.
我的孙儿孙女们圣诞节期间将呆在这儿.
The workers have to yell to be heard over the din of the engines
也就是“在嘈杂的引擎声间,工人们不得不大声喊叫才能听得见”