it is indispensable
Followed by 'que + subjunctive' or infinitive.
it is indispensable that you study.
It is indispensable to have prior experience.
—Can I participate without having studied this? —No, it's essential to have the basics.
It is indispensable to have prior experience.
—Can I participate without having studied this? —No, it's essential to have the basics.