方程x2+y2+2ax-by+c=0表示圆心为C（2，2），半径为2的圆，则a、

阅读理解。

      There are four seasons in a year: spring, summer, autumn and winter. 

      Spring is the best season of the year. The weather gets warmer and the days get longer. The crops begin to

grow. The trees turn green and flowers come out. 

      Summer comes after spring. It is the warmest season. It often rains and the crops grow fast. The best sport

in summer is swimming. Children often go swimming in rivers and lakes. 

      Autumn is a busy season. The days get shorter and the nights get longer. It is harvest time. The farmers are

busy. They are getting in the crops. 

      Winter is the coldest season of the year. Sometimes it snows and the fields are all white. Skating is the best

sport in winter. Many boys and girls often go skating. But the farmers are still busy. They are getting ready for

the next year.

1. How many seasons are there in a year? [ ]

A. Three

B. Four

C. Five

D. six

2. What is the weather like in spring? [ ]

A. Hot

B. Warm

C. Cold

D. Cool

3. Which season comes after spring?[ ]

A. Spring

B. Autumn

C. Summer

D. winter

4. What sport is the best in winter? [ ]

A. Cycling

B. Skiing

C. Skating

D. Swimming

5. What are the farmers busy doing in winter? [ ]

A. They are busy getting ready for the next year.

B. They are busy getting in the crops.

C. They are busy planting trees and flowers.

D. They are busy doing sports.

主诉牙第一次的处理为

A．消炎和镇痛药

B．开髓开放引流

C．开髓封失活剂

D．垫底银汞充填

E．拔除后修复缺失牙

主要沉积于上呼吸道的颗粒粉尘直径为（）

A.大于15μm

B.10～15μm

C.5～10μm

D.小于3μm

E.大于1μm

(12分)

Ⅰ．短周期元素组成的单质X₂、Y，标准状况下X₂的密度为3.17g·L^－1；常温下，Y为浅黄色固体。Z是一种化合物，焰色反应呈浅紫色(透过钴玻璃)；0.1mol·L^－1 Z的水溶液pH=13。X₂、Y 和Z之间有如下转化关系(其他无关物质已略去)

（1）写出常温下单质X₂与Z反应的离子方程式                                   

（2）已知C能与硫酸反应生成能使品红溶液褪色的气体

①D的化学式是         ；D的水溶液pH＞7，原因是(用离子方程式表示)                  

②将20mL 0.5mol·L^{－1 C}溶液逐滴加入到20 mL 0.2mol·L^－1 KMnO₄溶液(硫酸酸化)中，溶液恰好褪为无色。写出反应的离子方程式                                 

Ⅱ．下表是元素周期表的一部分，表中所列的字母分别代表某一元素．

某种金属元素的单质G，可以发生如下图所示转化：

其中化合物M是一种白色胶状沉淀；K的溶液与过量B的某种氧化物反应的化学方程式为___________________________；一种新型无机非金属材料由G元素和C元素组成，其化学式为        。

高速公路上发生的碰撞护栏事故，主要由于驾驶员在高速公路行车时行车间距不够造成。