上颌第一磨牙拔除时需要麻醉的神经有： 、 、 。下颌尖牙拔除时需要麻醉的神经

如图（a）为“研究平抛运动”的实验装置，斜槽末端B处已经水平，如图（b）是在斜槽末端B处对接了平板P．利用这套装置可以测量小物块Q与平板P之间的动摩擦因数，实验步骤如下：

①测量出斜槽末端高度h和平板P的长度L；

②将物块Q在A点由静止释放，测量出Q落地点距B点的水平距离S₁；

③水平对接平板P，如图（b）所示（P板的上表面与斜槽末端相切）；

④再次将物块Q在A点由静止释放，测量出Q落地点距P板右端的水平距离S₂；

试求出：（用实验中的测量量表示，重力加速度为g）：

（1）物块Q到达B点时的速度v_B=______；

（2）物块Q与平板P之间的动摩擦因数μ=______；

（3）已知实验测得的μ值略大于实际值，其原因除了实验中测量的误差之外，其它的可能是______．（写出一个可能的原因即可）．

长度为L=0.4m的轻质细杆OA，A端连有一质量为m=2kg的小球，如图所示，小球以O点为圆心在竖直平面内做圆周运动，通过最高点时小球的速率是1m/s，则此时细杆对小球的作用力为（　　）

A．15N，方向向上

B．15N，方向向下

C．5N，方向向上

D．5N，方向向下

小凡同学在实验室做“观察水的沸腾”实验，当水温为82℃时开始记录数据，以后每隔1min读一次温度计的示数，直到水沸腾一段时间后停止读数，其数据记录如下表所示。

（1）在记录第四次数据时，温度计的示数如图1所示，请将读数填在表内空格中。 

（2）请根据表格中的数据，在图2中作出水的温度随时间变化的图线。

（3）由图线可知，水在沸腾过程中温度的特点是________________________。

（4）实验结束后，同学们在交流时，发现各自测出的水的沸点大都不是100℃，可能原因是__________________________ （写出一点）。

                                                                 图1                                                          图2

阅读理解

     It was Thanksgiving morning. I was busy preparing the traditional Thanksgiving turkey when the

doorbell rang. I opened the front door and saw two small children in rags huddling together on the top

step.

     "Any old papers, lady?" asked one of them.

     I was busy. I wanted to say "no" until I looked down at their feet. They were wearing thin little

sandals(凉鞋), wet with heavy snow.

     "Come in and I'll make you a cup of hot cocoa."

     They walked over and sat down at the table. Their wet sandals left marks upon the floor. I served

them cocoa and bread to fight against the cold outside. Then I went back to the kitchen and started

cooking.

     The silence in the front room struck me. I looked in. The girl held the empty cup in her hands, looking

at it. The boy asked in a flat voice, "Lady, are you rich?"

     "Am I rich? Pity, no!"

     I looked at my wornout slipcovers(椅套). The girl put her cup back in its saucer(茶碟)carefully and

said, "Your cups match your saucers." They left after that, holding their papers against the wind. They

 had reminded me that I had so much for which to be grateful.

     Plain blue china cups and saucers were only worth five pence. But they matched.

     I tasted the potatoes and stirred(搅动)the meat soup. Potatoes and brown meat soup, a roof over

our heads, my man with a regular job, these matched, too.

      I moved the chairs back from the fire and cleaned the living room. The muddy marks of little sandals

were still wet upon my floor. Let them be for a while, I thought, just in case I should begin to forget how

rich I am.

1. Which of the following would be the best title for the text?

A. Lady, are you rich?

B. A story of Thanksgiving Day

C. Don't forget how rich you are

D. Does cups and saucers match well?

2. The writer let the two children come in and served them well because________.

A. she wanted to sell old papers to them

B. she wanted to invite them to her Thanksgiving party

C. she showed great pity and care on them

D. she had the same experience as them in the past

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

A. The girl thought the writer was rich just because she wanted to make the writer happy.

B. The writer had thought she wasn't rich because her supplies were not expensive.

C. If cups and saucers match well, they are a best pair even though cheap.

D. After hearing what they said, the writer seemed to understand what a rich life was.

4. The writer left the muddy marks of little sandals on the floor for a while to________.

A. show that she was a kindhearted lady

B. remind her that she shouldn't forget how rich she was

C. leave room for readers to think about what being rich is

D. prove that she had understood what meant being rich

压缩机中，制冷剂吸收热量，其温度和压力不变化