如果你及时归还我就把自行车借给你。
I can lend you my bike on condition that you return it on time.
只要你能及时归还，我就把这本书借给你。
I'll lend you the book on condition that you can return it in time.
若能及时将图书归还图书馆，我们将不胜感激。
We would appreciate the prompt return of books to the library.
你必须及时把书归还给图书馆。
你应该及时把这本书归还。
我们及时将书归还给图书馆是十分必要的。
It is necessary that we (should) return the book to the library on time.
我们及时将书归还给图书馆是十分必要的。
It is necessary that we (should) return the book to the library on time.
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