圈梁的主要作用是（）。A、装饰建筑外墙 B、增加建筑的整体性 C、提高墙体的承载力

某中学有学生270人，其中七年级108人，八、九年级各81人，利用抽样方法抽取10人参加某项调查，考虑选分层抽样和系统抽样两种方案，使用分层抽样时，将七、八、九年级 学生依次统一编号为1，2，…，270；使用系统抽样时，将学生统一随机编号为1，2，…，270，并将整个编号依次分为10段，如果抽得号码有下列四种情况：

①7，34，61，88，115，142，169，196，223，250；

②5，9，100，107，111，121，180，195，200，265；

③11，38，65，92，119，146，173，200，227，254；

④30，57，84，111，138，165，192，219，246，270。

回答以下问题：

（1）可能是系统抽样的是（    ）；

（2）不可能是分层抽样的是（    ）。

女性，35岁。近半年反复发热伴双手关节肿痛，甲周红斑，双下肢紫癜，实验室检查示血小板减少，尿蛋白阳性，补体降低。最可能的诊断是（）

A.类风湿关节炎

B.系统性红斑狼疮

C.血小板减少性紫癜

D.肾小球肾炎

E.血管炎

下列各项职权中不属于行政监察机关职权的是（ ）

A．建议权

B．检察权

C．调查权

D．行政处分权

将一小段通电直导线垂直于磁场方向放入某磁场中，导线会受到一定大小的安培力作用；若保持直导线长度和其中的电流不变，将它垂直于磁场方向放入另一较强的磁场中，发现导线所受的安培力会变大。下列说法中正确的是 (　　)

A．磁场的磁感应强度由导线所受的安培力决定

B．磁场的磁感应强度随导线所受的安培力的增大而增大

C．磁场的磁感应强度由磁场本身决定

D．在任何情况下，通电导线所受安培力的大小都能反映磁场的强弱

阅读理解。

     An Australian-based scientist announced yesterday he had made a step forward in forensic (用于法

庭的) DNA testing so that an individual can be identified by a single cell.      

     Ian Findlay, from the Australian Genome Research Facility at the University of Queensland, said

current DNA testing required 200 to 500 cells to gain a similar level of accuracy. "What we have done

has brought that down to one cell," Dr Findlay said after releasing details of his DNA testing technique

at a Sydney conference.    

     The technology could allow investigators to pick up DNA identities from plastic cards and even build

up a complete history of the people who have handled a paper document.

     "You'd have to wear a space suit to stop yourself from leaving traces. You can identify cells on the

paper, so you can work out where it's come from and who's touched it," he said.

     The technique could also be used to trace the thrower of a punch (打孔) from cells left behind on the

skin of their victim. Even the wearing of latex(橡胶)gloves would not help: small cells can pass through

the gloves, and the constant flow of genetic material given off by the human body would leave further

evidence.

     "We gained a skin cell from a document dating back 30 years and managed to gain a DNA

fingerprint. DNA evidence can remain fresh for decades, perhaps even centuries," Dr Findlay said.  "The

potential for this technology to solve unsolved crimes is great, "he said.    

     But Dr Findlay, named scientist of the year in 1998 by the European Society of Human Genetics, said

the new testing needed to be scientifically validated, which would take up to five years.      

     He said, "There are serious consequences taking on technologies too early. The public has to be sure

that they have the utmost confidence in the security and court systems."

1. The main advantage of the new technology is that ______.

A. it has brought down the cost of DNA testing

B. a single cell can identify an individual

C. a higher level of accuracy can be acquired with a single cell

D. it needs less than 200 cells to gain a certain level of accuracy

2. The underlined word" validated" means ______.    

A. proved true      

B. imagined good      

C. supposed commonly    

D. criticized strongly

3. According to Ian Findlay, the new technology can ______.

A. help to keep DNA evidence fresh for decades and even centuries

B. make the process of DNA testing much more simplified

C. help to pick up DNA identities more easily

D. be widely used in five years at most

4. The last paragraph suggests that ______.

A. the immediate adopting of the technology may cause mistakes

B. the public have acknowledged the new testing technology

C. it is safe to put the new technology into use now

D. Dr Findlay is quite sure of his new technology

5. The aim of the passage is to ______.

A. praise Ian Findlay for his work        

B. inform us of the wide use of DNA testing

C. report a piece of interesting news    

D. tell us a recent improvement in DNA testing