世界上最早的天文观象台位于（）。A、半坡遗址 B、大汶口遗址 C、陶寺遗址 D、牛河梁遗址

解下列方程：

（1）x²﹣2x﹣3=0；

（2）（x﹣1）（x+2）=4

（2010·辽宁鞍山，18）(5分)在测定空气中氧气含量的实验中，小强采

用了如图所示装置：在由两个注射器组成的密闭系统中留有25mL空气，给装有细铜丝的玻

璃管加热，同时缓慢推动两个注射器活塞，至玻璃管内的铜丝在较长时间内无进一步变化时

停止加热，待冷却至室温，将气体全部推至一个注射器内，观察密闭系统内空气体积变化。

(1)在实验加热过程中，交替缓慢推动两个注射器活塞的目的是            。

(2)写出该实验中反应的化学方程式                                      。

(3)小强测得实验结果如下：

反应前注射器内气体总体积	反应后注射器内气体总体积
25mL	22mL

 由此数据可以推算出他测定的空气中氧气的体积分数             2l％(填“>”、“＝”、 “<”)。造成该实验出现误差的原因可能是          。(填序号)

①没有交替缓缓推动两个注射器活塞；②读数时没有冷却至室温；③加入铜丝量太少；④加入铜丝量太多

(4)通过上面的实验，你学到的测量混合物中某成分含量的方法是                   

严重腹泻可引起（）

A.胃酸损失

B.碳酸氢盐丧失，造成酸中毒

C.肾脏对NaHCO重吸收代偿降低

D.引起碱中毒

E.引起高血钾

第二部分：阅读理解（共20小题;每小题2.5分，满分50分）

阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。

Proper arrangement of classroom space is important to encouraging interaction. Most of us have noticed how important physical setting is to efficiency and comfort in our work. College classroom space should be designed to encourage the activity of critical thinking.

We have entered the 21st century, but step into almost any college classroom and you step back in time at least a hundred years. Desks are normally in straight rows, so students can clearly see the teacher but not all their classmates. The message behind such an arrangement is obvious. Everything of importance comes from the teacher.

With a little imagination and effort, unless desks are fixed to the floor, the teacher can correct this situation and create space that encourage interchange among students. In small or standard-size classes, chairs, desks, and tables can be arranged in a variety of ways. The primary goal should be for everyone to be able to see everyone else. Large classes, particularly those held in lecture halls, unfortunately, allow much less flexibility.

Arrangement of the classroom should also make it easy to divide students into small groups for discussion or problem-solving exercises. Small classes with movable desks and tables present no problem. Even in large lecture halls, it is possible for students to turn around and form groups of four to six. Breaking a class into small groups provides more opportunities for students to interact with each other, think out loud, and see how other students’ thinking processes operate all essential elements in developing new modes of critical thinking.

In courses that regularly use a small group format, students might be asked to stay in the same small groups throughout the course. A colleague of mine, John, allows students to move around during the first two weeks, until they find a group they are comfortable with. John then asks them to stay in the same seat, with the same group, from that time on. This not only creates a comfortable setting for interaction but helps him learn students’ names and faces.

1. The primary purpose of desk rearrangement is _______.

A. for the teacher to divide students into small groups.

B. to make it possible for students to interact with each other.

C. for the teacher to find out how students think.

D. to give students more opportunities to practice speaking.

2. The expression “step back in time at least a hundred years” in Paragraph 2 is intended to convey the idea that _______.

A. there is not much change in educational idea over the past hundred years

B. critical thinking was encouraged even a century ago

C. college classrooms often remind people of their college life

D. a hundred years ago, desk arrangement in a classroom was quite different

3. The greatest advantage in allowing each student to find his own group might be that________

A. learning is made comfortable in this way

B. the teacher can easily remember students’ names and faces

C. the teacher saves the trouble in doing that

D. brighter students can help slower ones.

4. It is implied in the passage that ______.

A. students are allowed to changed groups throughout the course in John’s class

B. classroom interaction between students is essential to the teachers

C. a comfortable environment leads to higher working efficiency

D. new kinds of desks and chairs should be made

5. The author mentioned John in the last paragraph in order to ________

A. create a comfortable setting for interaction

B. introduce an approach of learning students’ names and faces easily

C. give an example that students stay in the same seat throughout the course.

D. describe a good seat-arrangement mode in courses with small group format.

在充分就业时，不存在失业。