4.135 certainty: 'must' and 'cannot'

You use 'must' to say that something is certain to happen because of particular facts or circumstances.

• Computer interviewing and rudimentary computer diagnosis must eventually lead to computer decision-making.

You use 'cannot' to say that something is certain not to happen because of particular facts or circumstances. You do not use 'must not'.

• Europe cannot hope to forge a united defence policy without first settling its internal quarrels.
• The repression can't last.