Sentence examples similar to deemed not obligatory from inspiring English sources

Some, though, were deemed not qualified.

Each was deemed not to have SARS.

It's not obligatory".

Music is not obligatory.

Rubbing noses is not obligatory.

Bookings are recommended but not obligatory.

It may be convenient practice, but it is not obligatory.

It's not obligatory, but it's appreciated.

(Gifts are certainly not obligatory). What says Miss Manners?

But the historical context was not obligatory in the curriculum.

And yet, and yet... "liking Shakespeare is not obligatory".