school was back in session "求这句话解析.

school was back in session "求这句话解析.
school was back in session "求这句话解析.

school was back in session "求这句话解析.
学校又开始上课了.
主语：school
谓语：was
表语：back in session.
词组in session的意思是:在上课.

翻译为：
学校恢复正常开课。

学校又开会了，或学校新学期又开学了。要看上下文。