A．People can call you back if necessary.
B．You can dial a special number free.
C．You don’t need to pay for long distance call.
D．You can get a credit coupon when you give the phone number.

A．Because it’s prohibited by the government.
B．Because it’s more inefficient than other alternative fuels.
C．Because it will destroy the ozone.
D．Because ft costs a tot to mass-produce.