( )1. —How much shall I pay for the phone call?
—You________. This is free of charge.
A．shouldn’t B．can’t C．don’t have to D．mustn’t
( )2. —May I leave the office before 5 o’clock in the afternoon?
—No，I’m afraid you ________.
A．needn’t B. wouldn’t C．mustn’t D．won’t
( )3. The outbreak of SARS tells us that a sound public health system ________ be built up and strengthened in our country.
A．should B．can C．will D．may
