To work and care for

• wait on
• minister to
• do for
• attend

To place food before (someone)

• wait on

To spend or complete (time), as a prison term

• do
• put in

To perform the duties of another

• officiate
• function
• act

To meet a need or requirement

• suit
• suffice
• do
• answer

To be an advantage to

• boot
• profit
• benefit
• avail
• advantage

To fulfill an obligation

• live up to one's duty
• discharge one's duty
• subserve
• acquit oneself of an obligation
• obey the call of one's country
• hearken to the call of duty
• hear duty's call
• complete
• carry out

To work for

• be in the employ of
• carry on a trade
• toil
• labor
• be employed by

To help

• be of assistance
• assist
• give aid

To serve at table

• help
• help one to food
• attend
• wait on

To obey

• agree
• accept
• follow