It isn't being used without an object. It's in passive voice.

First of all, there's an implied "was" before "displayed".  This disappears via a common mechanism in English grammar called _ellipsis_.  So the remaining "was" effectively applies both to "given" and "displayed".  

And both "was given" and  "..._was displayed_" are to be understood as _passive voice_.  

The **object** is _Ju's art_.

In active voice:

(Somebody) gave approval, and
(somebody) displayed Ju's art.