expression
should do; ought to do; must do
Literary or formal expression equivalent to すべき; used to express obligation or duty.
See also: すべき
我々はなすべきことをなすだけだ。
We simply do what we must do.
なすべき努力はすべて尽くした。
We have made every effort that should be made.
すべき is the modern, standard form; なすべき is more literary and formal.
From classical verb 為す (なす, 'to do') + べき (obligation auxiliary).