在同一断面测风次数不应少于5次，每次测量的误差值不应超过5％。

关于绿叶中的色素能够在滤纸上彼此分离的原因的叙述，错误的是[ ]

A．提取液中的不同色素的相对分子质量不同

B．在层析液中，溶解度高的色素随层析液在滤纸条上扩散速度快

C．层析液使色素溶解后因扩散速度不同而彼此分离

D．阳光的照射使各种色素能彼此分开

紧急情况是指发生下列情况之一，原定日机组发电组合和负荷分配不能满足安全运行需要，必须立即采取紧急处理措施的情况.（）

A.发、输、变电设备发生故障

B.输变电设备负载超过规定值

C.电网频率或者电压超过规定范围

D.线路功率值超过规定的稳定限额

阅读理解。

     Andy Steele lives just a few blocks from the campus of Black Hills State University in Spearfish,

S.D., so commuting (经常往返) to class isn't the problem. But he doesn't like lectures much, isn't a

morning person, and wants time during the day to restore motorcycles.

     So Steele, a full-time senior business major, has been taking as many classes as he can from the

South Dakota State system's online offerings. He gets better grades and learns more, he says, and

insists he isn't missing out on the college experience.

     "I still know a lot of people from my first two years living on campus, and I still meet a lot of people,"

he says. But now, he sets his own schedule.

     At least 2.3 million people took some kind of online courses, according to a recent survey by The

Sloan Consortium, an online education group, and two-thirds of colleges offering "face-to-face" courses

also offer online ones. But what were once two different types of classes are looking more and more

alike and often falling into the same pool of students.

     At some schools, online courses originally intended for non-traditional students living far from campus

have proved surprisingly popular with on-campus students. A recent study found 42 percent of the

students enrolled (登记) in its distance education courses were located on campus at the university that

was hosting the online courses.

     Numbers vary depending on the policies of particular colleges, but other schools also have students

mixing and matching online and "face-to-face" credits. Motives range from lifestyle to adapting a job

schedule to getting into high-demand courses.

     Washington State had about 325 on-campus undergraduates taking one or more distance courses last

year. As many as 9,000 students took both distance and in-person classes at Arizona State last year.

     "Business is really about providing choices to their customers, and that's really what we want to do,"

said Sheila Aaker, extended services coordinator (协调人) at Black Hills State.

     Many schools, such as Washington State and Arizona State, let departments and academic units

decide who can take an online course. They say students with legitimate academic needs-a conflict with

another class, a course they need to graduate that is full-often get permission, though they still must take

some key classes in person.

1. What is the purpose of the passage?

A. To introduce Steele to us, who prefers online courses.

B. To tell us about the development of campus courses.

C. To show the differences between campus courses and online courses.

D. To show more on-campus students are taking online courses.

2. We can learn from the passage that Andy Steele _______. 

A. lives far from the campus

B. knows none of his classmates

C. wants to have his own lifestyle

D. doesn't get good marks

3. Which of the following is NOT true according to the passage?

A. The undergraduates attend the online courses for different purposes.

B. It is expected that distance education is popular with on-campus students.

C. About 325 on-campus undergraduates took online courses in Washington last year.

D. Different colleges have different policies about online courses.

4. From what Sheila Aaker said in the passage, we can tell _______.

A. business is the most popular major in universities

B. colleges should provide more majors for students

C. where the similarity between business and colleges lies

D. why colleges offer online courses to on-campus students

学习了机械效率知识后，小明同学对“斜面的机械效率跟什么因素有关”这课题提出了一些值得探究的猜想：A．跟斜面的倾斜程度有关；B．跟斜面的粗糙程度有关；C．跟物体的重力有关．同时小明同学为了证实其中的部分猜想是否正确，设计方案并进行了如图所示探究，记录如下数据：

实验次数	斜面倾角	斜面粗糙程度	物重G/N	斜面高度h/m	拉力F/N	斜面长度s/m	有用功W有/J	总功W总/J	机械效率η
①	30°	粗糙	1	0.5	0.7	1	0.5	0.7	71%
②	30°	稍光滑	1	0.5	0.6	1	0.5
③	45°	粗糙	1	0.7	0.9	1	0.7	0.9	78%

（1）请你替小明在上表中的空格处填上适当的数据（小数位参照表中的相关数据）

（2）小明在实验中是如何改变斜面的倾斜程度的：______．

（3）此实验的研究方法与下列事例______（填写字母）相同：

A．引入“合力”的概念              B．保持电阻不变研究电流与电压的关系

C．将撬棒抽象为绕固定点转动的硬棒  D．用木块被推的距离来表示物体动能的大小

（4）通过对比实验①②数据，可验证猜想：______（填写字母）．

（5）通过对比实验①③数据，可以得出的探究结论是：______．

（6）若要验证猜想C，你的办法是：______．

骨肉瘤好发于（）

A.颅骨

B.骨盆

C.肋骨

D.干骺端的骨松质

E.椎骨