实际比计划节约开支8%，是把______看作单位“1”．

(一) 在验证“机械能守恒定律”的实验中，一同学进行如下操作：

① 将打点计时器水平固定在铁架台上

② 将长约0.5m的纸带用小夹子固定在重物上后穿过打点计时器。用手提着纸带，使重物静止在靠近打点计时器的地方

③ 先松开纸带，后接通电源，让重物自由下落，打点计时器就在纸带上打下一系列的点

④ 换几条纸带，重做上面的实验

⑤ 在打出的纸带中挑选第一、二两点间距接近2mm，且点迹清楚的纸带进行测量，先记下O点的位置，依次再取四个计数点A、B、C、D。求出相应位置对应的速度及其下落的高度

⑥ 将测量数据及计算结果填入自己设计的表格中

⑦ 根据以上测得的数据计算相应的和的值。验证机械能守恒定律

（１）、以上操作有错误的是_________________________;

（２）、某同学用上述验证机械能守恒的装置测定当地的重力加速度：如图纸带上1至9为连续点，打点计时器所用的电源50Hz,由纸带所示数据算出当地的重力加速度是______ ；若当地的重力加速度真实数值是9.8 m/s²，请任意写出一个测量值与真实值有差异的原因__________；

（二）某同学利用图（a）所示的电路进行电路实验．电路中R₁的阻值为20Ω，滑动变阻器R上标有“50Ω 2A”字样．闭合电键S，将滑片P从最左端向右移动到某位置时，电压表、电流表的示数分别为2伏和0.2安．当不断向右移动滑片P，使得电压表与电流表指针偏离零刻度线的角度恰好均为指针满偏角度的1/4时（两表满偏角度相同），如图（b）、（c）所示．则此过程中，两表指针偏转的方向相________（填“同”、“反”）；该电源的电动势为_____________V，内阻为_________W．

已知数列{a_n}中，a₁=1，S_n其前n项和，且a_n+1=2S_n+n²-n+1，

①设b_n=a_n+1-a_n，求数列{b_n}的 前n项和T_n；

②求数列{a_n}的通项公式．

Why can human beings outlast many faster four legged animals when running long distances Perhaps because early humans evolved as hunters on the hot African savannas. Humans developed the ability to release heat by sweating, but most mammals must pant, a function hard to regulate while running. Also, four-legged animals must adopt a pace that lets them breathe once in mid-stride; otherwise, the impact of the front legs hitting the ground will prevent deep inhalation. Humans can vary the number of breaths per stride, set a pace unsuited to the prey, and so eventually exhaust it.
The author’s explanation of why human beings have evolved as superior distance runners would be most weakened if it were shown that

A．early humans typically hunted animals that were less well adapted than humans for long-distance running.

B．early humans were only one of a number of species that hunted prey on the African savannas.

C．early humans hunted mainly in groups by sneaking up on prey and trapping it within a circle.

D．hunting was just as essential for later humans in colder climates as it was for early humans on the African savannas.

E．(E) human beings of today have retained the ability to run long distances but no longer hunt by chasing prey.

以下叙述中，错误的是______。

A．双击鼠标可以触发Db1Click事件

B．窗体或控件的事件的名称可以由编程人员确定

C．移动鼠标时，会触发MouseMove事件

D．控件的名称可以由编程人员设定

职业道德是所有从业人员在（）中应该遵循的行为守则，涵盖了从业人员与服务对象、职业与职工、职业与职业之间的关系。

A.职业活动

B.商业活动

C.社会活动

D.从业活动