trzeba

1. expresses the goodness of the following verb; it is needed, one ought to
2. expresses the naturalness or obviousness of the following verb; ought to, must
3. expresses the necessity or obligation of the following verb; it is needed, one ought to

było

it was (third-person singular neuter past of być)

zwolnić

1. to slow down, decelerate (to go slower)
2. to slow down, decelerate (to slow something down)
3. to dismiss, fire (an employee)
4. to downshift, change lifestyle to a less stressful one
5. to free up
6. to exempt (free someone from a duty or obligation)
7. to release (e.g. a button, clutch)
8. to become available for someone to use
9. to resign (to quit a job)

biegu

genitive/locative/vocative singular of bieg