性心理障碍及其分类。

如图所示，质点O在垂直x轴方向上做简谐振动，形成了沿x轴传播的横波．在t=0时刻质点O开始向上运动，经0.2s第一次速度为零，形成波形如图．由此判断在t=2.6s时刻，质点A、B的运动情况是( )

A．A点位于x轴的下方           

B．A点正往上运动

C．B点位于x轴的下方           

D．B点正往下运动

阅读理解。

    Most cities and towns in China have night markets every day. During the day, the

streets are quiet (安静的). At night, they become crowded (拥挤的) and lively (活跃的).

Usually people arrive at three or four in the afternoon. By 6:00, the streets are like

rivers of people.

    Night markets are fun places to shop in. You can buy clothes, shoes and many other

things. If the price is too high, you can bargain with sellers (卖者). You can also buy

nice food. When you are hungry, you can sit down for a meal. Smelly tofu is popular, but

it really smells bad.

    The best thing is everything at night markets is cheap.

1. Where can we find night markets? [ ]

A. In the countryside

B. In the daytime

C. In most cities and towns

D. In all the towns

2. What's the meaning of "bargain"? [ ]

A. 合同

B. 讨价还价

C. 希望

D. 交易

3. Can people eat nice food at nights markets? [ ]

A. Yes, he can.

B. Yes, they can.

C. No, he can't.

D. No, they can't.

4. Choose the best title (标题) of this article. [ ]

A. Shopping Mall

B. Night Shopping

C. Markets

D. Night Markets

5. The best advantage (优势) of night markets is _____.[ ]

A. you can eat delicious food

B. you can buy different things

C. you can walk around

D. you can have a good time without paying too much money

对于正规式0*（10*1）*0*，其正规集中字符串的特点是（）

A.开头和结尾必须是0 

B.1必须出现偶数次 

C.0不能连续出现 

D.1不能连续出现

第一台金属活字手摇印刷机的发明者是（）。

A.毕昇

B.谷登堡

C.摩尔斯

D.爱迪生

危险性