对一个由n个关键码组成的序列，借助排序过程选出其中最大的关键码，要求关键码比较次数和

上述哪一种属不稳定型骨折（）。

A．横突骨折

B．棘突骨折

C．椎体压缩20%

D．关节突关节脱位

E．椎板骨折

阅读理解。

     Plants that live in the rainforest have adapted in amazing ways to several very difficult conditions．

This means that the plant has changed something in its "body" or "habits" to make it easier to survive

in difficult conditions．There are several conditions they have had to adapt to．First,the soil of the

forest floor is shallow．Also,the soil of the rainforest is not very rich,or easy to grow in．Next is the

problem of very heavy rain which continues over a large part of the year．Finally,many plants of the

rainforest are food for animals that live there．

      The biggest problem that rainforest plants have to adapt to is the lack of sunlight in the rainforest's

lower levels．Plants have adapted to this problem in several ways．Many plants have very large

leaves．The large leaf is helpful because it has a bigger surface area．The bigger surface area a leaf

has,the more sunlight it can absorb．The canopy trees adapt by growing to be 100 feet tall so that

their leaves can grab all available sunlight．Other plants called lianas (climbing woody vines) have

adapted by rooting themselves in the soil of the forest floor and growing up the trees until they reach

the canopy layer．Still other plants,such as epiphytes,have adapted by growing directly on the trees'

trunks and branches in the canopy and understory layers of the rainforest．

     An adaptation to the large amounts of rainfall that many rainforest plants have is called "drip tips"．

Their leaves are tapered (逐渐变细) to a sharp point at the end．This allows water to run off the

leaf quickly．There are many other adaptations that rainforest plants have made to their environment．

These will be discussed in detail,as we investigate the plants of the rainforest!

1．Which of the following is a difficulty that the rainforest plants have to face?

A．Changes in their "body" or "habits"．

B．Soil that is not very deep．

C．Epiphytes that grow on trees' trunks．

D．The worsening of the natural environment．

2．How do lianas adapt to the environment in the rainforest?

A．They grow under big leaves for protection．

B．They rely on other plants to reach the canopy layer．

C．They change their leaf structure constantly．

D．They grow on other plants' branches．

3．The underlined word "This" in Para．3 probably refers to ________．

A．the takein of sunlight

B．the large amounts of rainfall

C．the leaves' having a sharp point at the end

D．water's running off the leaves quickly

4．What can be inferred about rainforest plants?

A．They have to face dangers not only from animals but also from each other．

B．Too little sunlight and too much water are the biggest problems they face．

C．Different kinds of plants have different ways to absorb sunlight．

D．All of their adaptations have been investigated in detail．

5．What would be the best title of the passage?

A．How Do Plants Adapt to the Rainforests?

B．Why Do Plants Change Themselves?

C．What Kind of Plants Is the Most Adaptable?

D．What Is the Best Place for Plants to Live in?

男性，25岁，突发心悸1小时来诊。既往曾诊断为；预激综合征。查体：心率220次／分。心电图示：QRS波增宽0．14～0．16秒，起始部粗钝，R-R间期不等。

预激综合征最主要的心电图特征是（）

A.PR间期<0.12秒，P波不正常

B.QRS波群宽度>0，11秒

C.QRS波起始部粗钝

D.继发$T-T改变

E.以上都不是

口腔颌面部撕脱伤，如撕脱组织无血管吻合，龈口腔颌面部血供丰富，在伤后6小时内，也尽可能复位缝合。

ICMP协议属于TCP/IP网络中的 (1) 协议，ICMP报文封装在 (2) 协议数据单元中传送，在网络中起着差错和拥塞控制的作用。ICMP有13种报文，常用的ping程序中使用了 (3) 报文，以探测目标主机是否可以到达。如果在IP数据报传送过程中，发现生命期(TTL)字段为零，则路由器发出 (4) 报文。如果网络中出现拥塞，则路由器产生一个 (5) 报文。

4（）

A．超时

B．路由重定向

C．源端抑制

D．目标不可到达