问题 单项选择题

某患者X线片显示残根根尖下方有1.5cm×1.0cm圆形低密度影像,周围包绕致密骨白线。该病最可能的诊断是()

A.含牙囊肿

B.成釉细胞瘤

C.根尖囊肿

D.牙源性角化囊性瘤

E.颌骨血管瘤

答案

参考答案:C

阅读理解

阅读理解。

     In Europe, people hold the fork in the left hand and the knife in the right throughout the meal, a

system that is generally agreed to be more efficient than the American zigzag (曲折的) method.

Americans hold both the fork and the knife in their right hands throughout the meal, so they continually

change their forks to the left hand when they have to cut their meat. It seems to be funny for the

Europeans to see Americans busy changing their dinner sets, making a lot of noises.

      A  few explanations for this American style are as follows:?

     (1) Americans are practical and efficient. Since most of us are right-handed, it is reasonable to

keep our working tools at all times in the right hand that can use them most efficiently.?

     (2) Americans, the master of the New World are rebels (叛逆者).They use the zigzag method to

break the rules in the Old World and in this way they are thumbing their nose at Mother England.

Americans are a restless kind. They do not like to sit in one spot for very long when dining.

     (3) Forced to do so, they respond by "playing" with the silver.?

     Whatever the reason for the practice, it is now certainly as American as apple pie. Europeans

recognize this and are quick to attack it as evidence of American innocence (无知) of form.

Arguments against the zigzag method rest not only on grounds of efficiency but also on those of

tradition. In Old World dining, the knife is held in the right hand continually because it can serve as

an instant defense against the uninvited intruders (入侵者). However, such alertness (警觉) is out

of place in the New World, as every American believes that this is the home of the brave. Americans

juggle their silverware, perhaps, to show that they are not afraid and that one of them holding a fork

is worth any number of them holding blades(刀).?

1. Americans use _______ to hold their fork to pick up the salad.?

A. the right hand

B. the left hand?

C. both hands  

D. either of the two hands?

2. As the masters of the New World, Americans use a different cutting method from that in the 

    Old World to_____.?

A. show their independence of Mother England?

B. show their disrespect to Mother England?

C. add a new tradition to those in Mother England?

D. show off their creativeness to Mother England?

3. In the last sentence, the word "juggle" probably means ____________.?

A. hold      

B. play with        

C. pick up            

D. lay down?

4. Also in the last sentence, the two "them" refer to ____________.?

A. Americans              

B. Europeans and Americans separately?

C. Americans and Europeans separately            

D. Europeans                    

5. Which of the following statements is NOT true? ?

A. European people hold the fork in the left hand and the knife in the right hand.

B. The zigzag eating method is related to American characteristics.?

C. The zigzag eating method has become an American feature.?

D. European people will use the American method because of its efficiency.

问答题 案例分析题

某研究所承担了一项宇航嵌入式系统的研制任务,本项任务技术难度大、可靠性要求高、进度要求紧,预计软件规模约在一万行以上。而该所原先承担的相关项目均是用汇编语言编写(软件规模较小,一般是几百行)。项目主管工程师将软件开发的论证工作分别布置给了王工和李工,要求他们根据本项目的技术要求,在一周内分别提出软件的实施方案。

①该宇航嵌入式系统由数据处理机、信号处理机及数据采集模块组成。信号处理机主要通过数据采集模块将大量不同时间周期的外部数据采集进来,进行预处理(如FFT变换)后提交给数据处理机;数据处理机根据功能要求完成各种计算处理工作,并将结果输出。为了达到数据处理机和信号处理机的标准化,这两类处理机均采用同种处理机的体系结构(如PowerPC7410)。整个系统工作的最大周期为1s,最小周期为5ms。数据处理机上任务分布如表12-16所示。

②一周后,王工和李工提交了各自的实施方案,其共同之处在于二者均提出采用操作系统及相应的软件开发环境。但是,王工和李工在选择什么样的操作系统及开发环境方面出现了较大分歧。王工的实施方案指出,为了满足本项目的技术要求,并有利于本所软件的长期发展,应选用具有硬实时处理能力的嵌入式实时操作系统及开发环境(如VxWorks);而李工的实施方案指出,操作系统主要完成对计算机资源的管理与分配工作,考虑到人们对操作系统及软件开发工具的熟悉程度,本项目应选用具有大众化的、开发人员容易上手的嵌入式操作系统(例如,WindowsCE、Linux)。

③在两人争执不下的情况下,项目主管工程师组织了相关专家对王工和李工提交的实施方案进行了评审。最后,专家组一致认为王工的方案切实可行,操作系统的选型论证充分、客观,可以作为本所未来几年中相关项目的软件开发的基本环境。同时专家组还就具体实施选择嵌入式实时操作系统及开发环境产品时应着重考虑的相关问题提出了几点建议。

根据本项目中任务的时间性能参数,请用200字以内文字(也可用图示)描述任务的被调度关系,并分析系统是否可调度(暂不考虑操作系统的时间开销)。