爱护图书,按时归还用英语怎么说快

二楼的翻译基本正确.
最正确的译法是：
Take care of books and return in time.
说明：
通常用 in time,不是 on time
in time = in the course of timee.
(在指定的时间内)
on time = at the appointed time; punctual or punctually.
(在约定的具体时间,严格准时的)
Take care of books and return on time.
意思是：爱护图书,最后一刻准时来还(好像劝人不到最后一刻不要还).
Take care of books and return in time.
意思是：爱护图书,按时归还(不要迟于最后时间).

Love books, timely return.

Treasure a book , returning on time

您好！
take care of books and return on time