市场供给曲线与市场需求曲线的焦点为均衡点，关于均衡点的特点不包括（）。 A.存在性

小明把一根70cm长的木棒放到一个长、宽、高分别为30cm、40cm、50cm 的木箱中，他能放进去吗？答：（      ）（填“能”、或“不能”）

某同学和你一起探究弹力和弹簧伸长的关系，并测弹簧的劲度系数k。做法是先将待测弹簧的一端固定在铁架台上，然后将最小刻度是毫米的刻度尺竖直放在弹簧一侧，并使弹簧另一端的指针恰好落在刻度尺上，当弹簧自然下垂时，指针指示的刻度数值记作L₀；弹簧下端挂一个50g的砝码时，指针指示的刻度数值记作L₁；弹簧下端挂两个50g的砝码时，指针指示的刻度数值记作L₂……

（1）下表记录的是该同学已测出的6个值，其中有两个数值在记录时有误，它们的代表符号分别是_____和____________。测量记录表：

（2）实验中，L₃和L₇两个值还没有测定，请你根据上图将这两个测量值填入记录表中；

（3）为充分利用测量数据，该同学将所测得的数值按如下方法逐一求差，分别计算出了三个差值：d₁=L₄-L₀=6.90cm，d₂=L₅-L₁=6.90cm，d₃=L₆-L₂= 7.00cm。请你给出第4个差值d₄=________=__________cm；

（4）根据以上差值，可以求出每增加50g砝码的弹簧平均伸长量△L，△L用d₁、d₂、d₃、d₄表示的式子为：△L=___________，代人数据解得△L=__________cm；

（5）计算弹簧的劲度系数k=_____________N/m （g=9.8 m/s²）。

There is no question that fewer teenagers are on the roads in the US.

In 1978, 50% of 16-year-olds had got their first driving licence. In 2008, according to the US Transportation Department, it was just 30%. The number of those aged 19 and under with driving licences has also been declining since 1978, when 11, 989, 000 had licence. In 2010, it was 9, 932, 441, or 4.1% of American drivers.

In the UK, 683, 273 teenagers have driving licences- just 1.85% of total licence holders, according to Department of Transport figures from September 2010.

But the decline in the US may have more to do with tougher tests and the introduction of the new rule in many states, which force drivers aged under 16 to be with licensed drivers of 21 years and older when driving.

In recent years, the annual number of journeys being made by American drivers of all ages has declined clearly for the first time ever. Car use began falling in 2007, when average petrol prices almost doubled to $4.12 a gallon, and the economy became worse.

But there are signs that it is getting back to normal and American remains a country on wheels. It has a higher number of cars per head of population than any other country in the world.

“Cars will always be a popular means of transportation in America. You have to take into consideration some places don’t have access to public transportation. Cars are the only way some people can get around,” says Kristin Nevels. This makes driving necessary in some rural states, where about twice as many teenagers are on the road than in big cities.

小题1:The underlined word “declining” in the second paragraph most probably means “__________”.

A．rising

B．dropping

C．improving

D．holding小题2:In recent years cars are used less than before mainly because of __________.

A．traffic jams

B．harder tests

C．expensive petrol

D．worst economy小题3:We can learn from the last paragraph that Kristin Nevels __________.

A．doubts the popularity of the car use in the future.

B．thinks American people can not live without cars.

C．holds confident attitude to the cars’ future in America.

D．believes America should build up its public transportation.小题4:What can be inferred from the text?

A．The UK has more teenager drivers than the US.

B．A 15-year-old boy cannot drive alone in the US.

C．The US has very developed bus transportation system.

D．Big cities have more teenager drivers than rural areas in the US.

建筑与结构工程可划分为（）等四个分部。

A.地基与基础

B.主体结构

C.门窗

D.建筑装饰装修

E.建筑屋面

通用厂房、国有建设用地使用权，最高抵押率通常不超过50％。