The request that---------- ( 我借的书还回图书馆)by next Fridaythe books that i borrowed be returned to the library为什么是 be returned to这里不是该表示将来、被动吗?

The request that---------- ( 我借的书还回图书馆)by next Fridaythe books that i borrowed be returned to the library为什么是 be returned to这里不是该表示将来、被动吗?
The request that---------- ( 我借的书还回图书馆)by next Friday
the books that i borrowed be returned to the library
为什么是 be returned to这里不是该表示将来、被动吗?

The request that---------- ( 我借的书还回图书馆)by next Fridaythe books that i borrowed be returned to the library为什么是 be returned to这里不是该表示将来、被动吗?
the books that i borrowed (should ) be returned to the library.
这是中间省略了一个should .should 后面接动词原形.能理解吗?
The request that----the books that i borrowed (should ) be returned to the library------ ( 我借的书还回图书馆)by next Friday
我从图书馆接的数应该（必须,需要）在下周五前归还图书馆.

英语里里面be。。。。。to句型就已经含有了将来的意思。表示的是在短期内的，可以确定的，有日程安排的将来。而be 前面省略了一个Should 。