What do you do if you are hit in the mouth and one of your teeth is knocked out?

What do you do if you are hit in the mouth and one of yourteeth is knocked out? A dentist(牙医)may be able to put the tooth back in for you,but you have to get to the dentist first．In the meantime, youhave to store the tooth so that it will stay healthy．

The simplest thing to do is put the tooth back into yourmouth, or you could put it in milk．Frank Courts, adentist at the University of Florida, worked with other researchers to find thesafest way of keeping knocked-out teeth．He tried puttingteeth into milk, into water, and into cell-culture medium(细胞培养液)．He also tried, just drying the teeth in the openair．He used teeth that had to be removed from people’s mouthsfor various reasons．The teeth were put into one of the solutions(溶液)orstored in the air for one hour．Then cells from the root of the teeth werescraped-off the teeth．Dr．Courts and the others then studied how healthythese cells were．

The cell-culture medium worked best to keep a knocked-outtooth healthy outside the mouth．However, few people keep cell-culture mediumhandy at home or in school．

The next best thing was milk．But Dr．Courtssaid that the best thing of all was to wash the tooth and put it right backinto its socket(牙槽)in the mouth．For some people,though, this is just too painful or upsetting．So milk will do,until you get your tooth (and your mouth)to a dentist．

1.This passage is mainlyabout             ．

A. how a dentist can save a knocked-out tooth

B. how to keep a knocked-out tooth healthy

C．how Dr．Courts and otherresearchers made their experiments

D．how to put a knocked-out tooth back into itssocket

2.The best way to keep a knocked-out tooth healthy outsidethe mouth is to store it       .

A．in cell-culture medium    B．inmilk     C．in water    D．inthe open air

3.Milk can be used instead of cell-culture medium to put aknocked-out tooth in because     ．

A．milk works better to keep the toothhealthy  B．milk causes less pain

C．cell-culture medium is not usuallyhandy    D．cell-culture medium is more expensive

4.“Dr．Courts said that the best of al1 was to wash thetooth and put it right back into its socket in the mouth．”Inthe sentence, the word “best” means             .

A．cheapest andhealthiest                 B．least painful and cheapest

C．quickest and leastpainful               D．easiest and healthiest

试题答案

【答案】

1.B

2.A

3.C

4.D

【解析】略