⑴（6分）实验小组利用光电计时器验证物块沿斜面下滑过程中机械能守恒，装置如图甲．让小物块从斜面顶端滑下，若测得小物块通过A、B光电门时的速度为v₁和v₂，AB之间的距离为L，斜面的倾角为α，重力加速度为g.

①图乙表示用螺旋测微器测量物块上遮光板的宽度l，由此读出l=________mm.

②若实验数据满足关系式              则验证了物块沿斜面下滑过程机械能守恒.

③本实验的误差主要来源于斜面对物块的             而造成物块机械能的损失.

⑵(12分) 如图甲是某电器元件的伏安特性曲线，有实验小组想用伏安法验证该伏安特性曲线，已有符合实验要求的电压表V（内阻约为10kΩ）；滑动变阻器R；直流电源E（电动势6V，内阻不计）；开关S和导线若干，另有电流表A₁（量程0~50mA，内阻约为50Ω）、电流表A₂（量程0~300mA，内阻约为10Ω）可供选择.

①从图像可判断该元件的电阻随温度的增大而      .

②电流表应选用     （填A₁或 A₂）.

③图乙实物图中，已正确连接部分电路，请完成余下电路的连接.

④请完成主要实验的步骤：

A、连接好实验电路，把变阻器的滑动片调到          （A或B端）；

B、闭合开关，               ，使通过元件的电流从小到大变化，读出数据．

语法填空。

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号

中词语的正确形式填空，并将答案填写在相应位置上。

     I was on my way to the Taiyetos Mountains. The sun was setting when my car 1______ (break) down

near a remote and poor village. Cursing my misfortune, I was wondering where I was going to spend the

night when I realized that the villagers who had gathered around me were arguing as to 2______ should have

the honor of receiving me 3______ a guest in their house. Finally, I accepted the offer of an old woman who

lived alone in a little house. While she was getting me 4______ (settle) into a tiny but clean room, the head of

the village was tying up his horse to my car to pull it to 5______ small town some 20 kilometers away 6______

there was a garage.

     I had noticed three hens running free in my hostess's courtyard and that night one of them ended up in a

dish on my table. 7______ villagers brought me goat's cheese and hone. We drank together and talked 8______

(merry) till far into the night.

     When the time came for me to say goodbye to my friends in the village, I wanted to reward the old woman

9______ the trouble I had caused 10______.