12．
Bad breath，or halitosis（口臭），can be a serious problem．
Bad breath is caused by some germs（細菌） that grow in the month．When you don't brush in a right way，germs will leave between your teeth and make your breath smell bad．Certain foods，especially ones like garlic and onions can cause bad breath．Smoking can also make bad breath．
Some people say that mouthwash（漱口水） will make bad breath go away，but it isn't true．It only stops bad breath for a short time．
Some people also say that if you brush your teeth，you will not have bad breath．But the truth is that most people only brush their teeth for 30to 45seconds．It just doesn't work．To clean all your teeth，you should brush for at least 2minutes and at least twice a day．Remember to b rush your tongue，too-germs love to stay there．
If you do brush properly，but your bad breath still exists，visit your dentist for cleanings．You may have a medical problem like germ disease．
If you don't want to have bad breath，make sure you're taking care of your teeth and month well．
46．What can cause bad breath according to the passage？A
A．Germs，certain food and smoking
B．Germs，vegetables and drinking
C．Drinking，smoking and germs
D．Teeth，germs and smoking
47．The underline word"garlic"meansB in Chinese．
A．蔬菜 B．大蒜 C．橄欖 D．茄子
48．How long do most people brush their teeth according to the passage？D
A．For 30seconds．B．For 45seconds．
C．For 30to 45seconds．D．For 2minutes．
49．Which is the right way to brush your teeth？B
A．To brush your teeth only in the morning．
B．To brush your teeth for at least 2minutes and at least twice a day．
C．To brush your tongue twice a day．
D．To brush your teeth before and after meals．
50．Which of the following is true？B
A．Mouthwash is the best thing to take away bad breath．
B．Bad breath may be a medical problem．
C．There aren't any germs on your tongue．
D．You don't need to go to the dentist if you have a bad breath．
