18．Bad breath can be a major problem．The good news is that it can often be prevented with some simple steps．
Bad breath is caused by certain bacteria that grow in the mouth．When you don't brush regularly，bacteria accumulate in your mouth and between your teeth．（36）ACertain foods，especially ones like garlic and onions that contain pungent （辛辣的）oils，can contribute to bad breath because the oils are carried to your lungs and out through your mouth．（37）CSome people think that as long as you brush your teeth，you shouldn't have bad breath． （38）EThat，however，just doesn't remove the smell．To sufficiently clean all the surfaces of your teeth，you should brush for at least 2minutes at least twice a day．
Many people believe that if you breathe into your hand，you'll know when you have bad breath．But it's wrong!（39）G3When you talk，you tend to bring out the smell from the back of your mouth （where bad breath starts），which simply breathing doesn't do．Also，because we tend to get used to our own smells，it's hard for a person to tell if he or she has bad breath．
If you're concerned about bad breath，make sure you're taking care of your teeth and mouth properly．If you brush properly and visit your dentist for regular cleanings but your bad breath persists，you may have a medical problem．（40）BThey can figure out if something else is behind your bad breath and help you take care of it．
A．These bacteria make your breath smell．
B．In that case，call your doctor or dentist．
C．Smoking is also a major cause of bad breath．
D．Remember to brush your tongue，too-bacteria love to hang out there．
E．The truth is that most people only brush their teeth for 30to 45seconds．
F．When you breathe，the smell bounced back by your hand can be easily sensed．
G．When you breathe，you don^use your throat the same way you do when you talk．
