根据团体的规模，可以把团体分为( )。 A．正式团体 B．非正式团体 C．大团体

将一根铜丝在酒精灯上加热使其表面变黑，化学方程式为 ______，然后，将其浸入盛有稀H₂SO₄的试管中，充分反应后，溶液变为 ______色，化学方程式为 ______．最后将该铜丝浸入Hg（NO₃）₂溶液中，过一会儿，可观察到铜丝表面附着一层 ______色物质，化学方程式为 ______．

阅读理解。

                                                          The Guitar Player

      One day Tony was crossing the road when he was hit by a car. He fell and broke his arm.

      An ambulance soon arrived and took Tony to a hospital. There a doctor operated on his arm. Then he

put the arm in a cast (石膏). Tony could not move it at all.

      "You must keep your arm in a cast for six weeks," the doctor said. "That will give the broken bone a

chance to heal (愈合)."

      At the end of six weeks Tony went back to the hospital. The doctor cut the cast with a large saw (锯).

Then he took Tony's arm out of the cast.

      "Can you move your arm, Tony?" he asked.

      Tony tried to move his arm. At first it was difficult, but soon he was able to move it a little.

      "Yes, it's fine," he said. "Thank you very much."

      "In a few days it will be as good as new, "the doctor said. Just exercise it a little,"

      "Will I be able to play the guitar?" Tony asked.

      The doctor smiled. "Of course you will," he said. "You'll have no problem."

      "That is good news," Tony said. "Because I couldn't play it at all before."

1. How long did he have to keep his arm in the cast? [ ]

A. About 40 days.

B. A few days.

C. Two weeks.

D. Two months.

2. What did the doctor tell Tony to do after the cast was taken off?[ ]

A. Keep his arm still.

B. Exercise his arm.

C. Play the guitar.

D. Operate on his arm.

3. Why was Tony pleased? [ ]

A. He could play the guitar before he broke his arm.

B. The doctor taught him how to play the guitar.

C. He thought he would now be able to play the guitar.

D. The doctor said he would never play the guitar again.

4. Which statement is NOT true?[ ]

A. It took the broken bone six weeks to heal.

B. The cast was so hard that the doctor had to cut it open with a special tool.

C. Tony liked playing the guitar but he didn't know how to play it.

D. A traffic accident happened to Tony on his way to school.

以下各项特点中，属于线性表的顺序存储结构的是( )。

A．线性表中所有元素所占的存储空间是不连续的

B．线性表的数据元素在存储空间中是随便存放的

C．线性表中所有元素所占的存储空间是连续的

D．前后件两个元素在存储空间是随便存放的

办理销号当月是否收取最低消费？

DCS系统直流工作接地有时又称为数据高速通路逻辑参考地、要求最高，接地电阻必须小于（）。

A.0.5

B.1

C.2

D.4