若10把钥匙中只有2把钥匙能打开某锁，则从中任取2把能将该锁打开的概率为( )。

下列物理图象中，反映物理量之间关系正确的是[ ]

A．汽车做匀速直线运动的图象

B．铅的质量与体积的关系图象

C．汽车做匀速直线运动的图象

D．海波的融化图象

说明理由：                                                                                                           ．

脚手架底部的构造应符合下列哪些规定要求？（）

A．每根立杆底端应设底座或垫板，且应设纵向、横向扫地杆 

B．纵向扫地杆距底座上皮不大于200mm，并采用直角扣件与立杆固定 

C．纵向扫地杆距底座上皮不大于1000mm，并采用直角扣件与立杆固定 

D．横向扫地杆应采用直角扣件固定在紧靠纵向扫地杆下方的立杆上 

E．横向扫地杆设在距底面上0、8m处

Part 4

Questions 26-45

·Read the following passage and decide which answer best fits each space.
·For questions 26-45, mark one letter A, B, C or D on the Answer Sheet.
Participation (26) high school sports is not a constitutional right. (27) , it is a privilege, paid for by taxpayers, open to students who promise to (28) certain conduct requirements on and off the field. One of these promises is to (29) from using drugs. Drug use is a serious problem among high school students. Studies show that as many as 500, 000 high school students use muscle-pumping, life-destroying substances such as steroids. Many more use illegal drugs, (30) cause discipline problems and (31) the stage for lifelong (32) .
Drug testing works to (33) and identify use. That is why drug testing is required to compete in the Olympics, the National Collegiate Athletic Association and the National Football League. (34) drug testing was instituted by these organizations, use of performance- (35) drugs has been greatly reduced. We should want (36) in schools.
Indeed, many athletes (37) testing programs, and no wonder. Without testing, athletes have to choose between drug use and a competitive disadvantage (38) the field.
Those who challenge the need for drug testing may be forgetting (39) it is like be an adolescent. Peer pressure is enormous, and one of the few effective counter-weights is the fear of being caught. More importantly, once drug use is (40) , a school can (41) to the student before he or she gets addicted or arrested.
For 25 years, public schools (42) by federal judges and civil libertarians, with results everyone can see. It is time (43) decisions on how to run public schools locally (44) officials. There is nothing unconstitutional about asking those who gain the advantages of school-sponsored athletics to contribute to the safety of other players, the integrity of the game and their own well-being. The Supreme Court should leave these programs (45) .

A．break out

B．reach out

C．stretch out

D．check out

成人股骨头缺血坏死股骨头塌陷的X线征象是（）

A.股骨头皮质成角

B.台阶征

C.双边征

D.裂隙征

E.股骨头节裂

在研制“两弹一星”的过程中，广大科研工作者培育和发扬了一种崇高的精神，这就是（）

①热爱祖国、无私奉献

②自力更生、艰苦奋斗

③独立自主、不怕牺牲

④大力协同、勇于登攀

A.①②③

B.②③④

C.①②④

D.①③④