问题描述：
checked out back
Excuse me,I received a letter that I am supposed to return a book that I checked out back in September ,it’s called Modern Social Problems.
这是图书馆场景,想知道check out back
Excuse me,I received a letter that I am supposed to return a book that I checked out back in September ,it’s called Modern Social Problems.
这是图书馆场景,想知道check out back
问题解答：
我来补答展开全文阅读