C.Do you have healthy habits? How often do you brush your teeth? How often do you go to the dentist(牙醫)? Don't wait until you have a toothache. Here are some tips(秘訣) for you：  1. Brush your teeth in the morning, after meals, and before going to bed.  2. Change your toothbrushes every three months.  3. Learn to brush your teeth in the right way.  4. Use the dental floss(牙線) and mouthwash(漱口水).  5. Go to the dentist every six months.6. Don’t eat sweet food very often.
【題組】4. () How often should we go to the dentist?
(A)Six times a year.
(B)Never.
(C)Twice a year.
(D)Three times a day.