English is not a language with rich inflection, so from the verb alone it’s hard to get information about person and number.
walk
present tense
can be any number and person, except 3rd person
singular, because that would be walks
work
same as above
worked
past tense.
can be any number and person
have
present tense
any number and person, except 3rd person
singular (he has)
For Dutch it is a bit easier to tell:
loopt
present tense (past tense is liep)
must be 2nd or 3rd person singular
(ik loop – jij loopt – hij loopt – wij/jullie/zij
lopen)
werken
present tense
can be 1st, 2nd or 3rd person
(ik werk – jij werkt – hij werkt - wij/jullie/zij werken)
must be plural
werkte
past tense
can be 1st, 2nd or 3rd person
(ik werkte – jij werkte – hij werkte – wij/jullie/zij
werkten)
must be singular
werkten
past tense
1st, 2nd or 3rd person
must be plural
see above