问题 单项选择题 A1型题

下颌远中、舌侧倾斜的基牙,设置环形卡环时,其卡环臂尖端应位于基牙何部位 ()

A.基牙近中缺隙侧邻面

B.基牙颊侧近中倒凹区

C.基牙无远中邻面

D.基牙侧近中倒凹区

E.基牙颊侧远中倒凹区

答案

参考答案:D

解析:

为延长余留牙使用时间,在卡环的设计上尽量使用连续卡环、环形卡环,可以固定松牙,使多个牙共同承担固位力,有利于牙周病的恢复;当下颌远中、舌侧倾斜的基牙,设置环形卡环时,其卡环臂尖端应位于基牙侧近中倒凹区。

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     __1__It is a new term in today's tourism industry.But in an age of growing environmental awareness,it is not too difficult for us to imagine and understand this new form of holiday.

     Ecotourism,which is considered as a kind of responsible tourism,is typically defined(定义)as travel to

places where special and unusual plants,animals and cultural heritages(遗产) are the main attractions.  

__2__   Therefore,programs concerning the protection of some natural and cultural spots also form a part of ecotourism.

     Ecotourism is developing at great speed.According to a recent report by the World Tourism

Organization,ecotourism in recent years has enjoyed an annual growth of about 5% worldwide.  __3__  

They include bird watching,hiking,diving,photography and taking part in various kinds of local cultural

events.

      __4__   However,it looks like some smaller towns and country areas may well become the new

destinations for people to visit tomorrow because they are rich in ecological,cultural and historical

resources(资源).

     Ecotourism has been gaining increasing recognition and popularity mainly for the relaxing,natural and

vivid experience it offers to tourists.People are attracted to nature and long to be close to it.However,a

conflict between nature and human beings is unavoidable.  __5__  

A. The definition of ecotourism is beyond words.

B. It takes ecology and culture into consideration.

C. You may not be very familiar with "ecotourism".

D. More than 80 activities have been listed for ecotourism.

E. People can have great fun enjoying nature through ecotourism.

F. Big cities are still the major places that attract tourists in our society today.

G. How to protect natural resources while taking advantage of them is of great importance