Now ______ your turn to keep guard.

A．you must pay for what you have bought immediately
B．you don't have to pay for what you have bought
C．you must pay for what you have bought once in a while
D．you can pay for what you have bought either at one time or at several times

A．be sure that your expenses are not larger than your savings
B．try not to lose your money through carelessness
C．try to avoid thief
D．learn to save your money