do duty for

当…用，起作用

divvy, Dixie, Dixieland, DIY, dizzily, dizziness, dizzy, dizzying, DJ, dl, DLitt, dm, DM (also D-mark), DMus, DNA, do, do a good job, do away with, do by sb., do down, do experiment on, do for, do for sb, do good to, do harm (to), do harm to, do it yourself, do justice, do not have the heart, do one's best, do one's bit, do one's duty, do one's hair, do one's level best, do one's utmost, do oneself proud, do over, do research into, do sb in, do sb. a favour,