we are going on a trip to the zoo( )(on this saturday ,in this saturday ,this saturday ,in

we are going on a trip to the zoo( )(on this saturday ,in this saturday ,this saturday ,in
we are going on a trip to the zoo( )(on this saturday ,in this saturday ,this saturday ,in

we are going on a trip to the zoo( )(on this saturday ,in this saturday ,this saturday ,in
this Saturday

我们要去动物园（）（这在本星期六，星期六，星期六，在 星期六

This saturday.
(on) is already implied in context

this saturday,
this morning,
next monday, etc..