12．Losing a baby tooth can be fun for a kid．You can put it under your pillow and look forward to finding some money there in the morning．And then you can watch your new permanent（永恒的） tooth grow in its place．
But if a permanent tooth falls out，that's a problem．There isn't another one under the gum（齒齦） that can replace it．Unfortunately，this happens to some older people．And if permanent teeth fall out or need to be pulled，an older person might need dentures（假牙）．
Dentures，known as false teeth，are a set of replacement teeth for any teeth that are missing．There are partial dentures，which take the place of only a few teeth and prevent the others from changing position．If all the teeth are gone，the person would need complete dentures，which replace every tooth in the mouth．
Dentures can cause pains at first and take little time to get adjusted to．They also need special care．They should be brushed daily with a special denture brush and cleanser and soaked（浸泡） in denture solution when not in the mouth．
Dentures are important for the old because，without teeth，it's hard to smile，talk，and eat properly．But it can be a little weird if you see someone take out his or her dentures．It can also be strange to see someone，like a grandparent，without dentures in because he or she won't have any teeth．Try not to make fun of the person because this could cause hurt feelings．
People usually lose their permanent teeth due to periodontal disease（牙周炎），or gum disease，which is caused by bacteria that attacks the gums．Diseased gums aren't strong and healthy，so teeth can get loose and fall out．Older people often have many cavities（洞） that have been filled over the years，and these fillings can weaken over time，leading to more tooth problems．
54．If one of your baby teeth falls out，you．C
A．should have a false tooth fixed in its place B．have to put it under your pillow at once
C．will gain a permanent tooth in future D．can exchange it for some money
55．A person wearing dentures．C
A．should brush them with a special denture brush every few days
B．will take a very long time to adjust himself or herself to them
C．will experience unpleasant feelings at the beginning of fixing them
D．should use denture solution to soak them in his or her mouth
56．What does the underlined word"weird"mean in the fifth paragraph？C
A．inconvenientB．excited C．uncomfortable D．impolite．
分析 本文是一篇科教類閱讀，文章主要介紹了當(dāng)人的那永恒的牙齒松動的話，就要考慮安假牙了，尤其對老年人來說．其次介紹了假牙的用處，重要性等等．
解答 54-56 CCC
54．C細(xì)節(jié)理解題．根據(jù)第一段You can put it under your pillow and look forward to finding some money there in the morning．And then you can watch your new permanent（永恒的） tooth grow in its place．可知你可以把掉的牙放在枕頭下面然后盼望在早上找到一些錢．然后你就可以看到新的永恒的牙會從掉的地方長出來．故選C．
55．C細(xì)節(jié)理解題．根據(jù)第四段should be brushed daily with a special denture brush可知每日都要清洗，故A不正確．根據(jù)第四段Dentures can cause pains at first and take little time to get adjusted to．可知需花費很少的時間來適應(yīng)假牙，故B不正確．根據(jù)第四段soaked（浸泡） in denture solution when not in the mouth．可知并不是在嘴里浸泡，故D不正確．根據(jù)第四段Dentures can cause pains at first，可知假牙在最初使用時會產(chǎn)生一些痛苦的．故選C．
56．C詞匯辨析題．根據(jù)第五段But it can be a little weird if you see someone take out his or her dentures．It can also be strange to see someone，可知如果你看見有人取出她的假牙，你可能會覺得有不舒服．由此可知，"weird"的意思是"不舒服的"．故選C．
點評 本文考察學(xué)生的理解推斷能力，抓住文章的關(guān)鍵詞，采用尋讀的方法查找細(xì)節(jié)，能根據(jù)已知的結(jié)果推測導(dǎo)致結(jié)果的可能原因．
