In fact, it is preferable that you aren't.
It is preferable that they be clean, efficient, gas-fired plants that emit few pollutants.
To be sure, it is preferable that all ongoing investigations proceed to their legal conclusion.
As to which approach is preferable, that seems to me a matter of personal choice.
If you are a full-time student, it is preferable that you register for required courses as soon as possible.
It is preferable that your recommender is someone who knows of your potential to succeed in research.
"If the Syrians want to reach an agreement, and it is preferable that an agreement be reached, good".
It is preferable that a better and truer version of events, however incomplete, should be constructed, even now, from the rubble of the past.
(Either assign the topics or allow students to choose their own. It is preferable that every pair write about a different topic).
Maybe it is preferable that British democracy be tempered by a few hundred unelected and average lords than cede hegemony to a bunch of professional pols.
To fully benefit from undersampled MRI, it is preferable that the design of adaptive sampling functions be performed online immediately before the main scan.
