简述社会群体的分类及其标准时什么？

下列有关催化剂的说法正确的是（　　）

A．催化剂只能加快化学反应的速率

B．催化剂可以改变化学反应的速率

C．催化剂在化学反应前后性质改变

D．催化剂在化学反应前后质量发生变化

我国南联盟大使馆被炸，是在1999年的（）战争中。

A、海湾战争

B、科索沃战争

C、阿富汗战争

D、伊拉克战争

The video rooms have been open since Jan. 2. If successful, the chain hopes to expand the service to other provinces, or even other countries. In addition to the food, customers pay 200 yuan per hour for using the room.

''The video rooms have been fully booked in February,'' said Chen Yu, manager of the Wangfujing branch. The Video room in Beijing is about 30 square meters and large enough for six customers.

''Many customers prefer to use the room for dinners rather than lunch,'' Chen said, adding the average age of customers who booked the video hotpot(火锅) is about 30.

''The whole process is very smooth. The image and the voice transmission(转换) are as good as those of video conferencing at work, ''said one of Chen's colleagues surnamed Luo.

''I have a lot of friends in Beijing, whom I haven’t met for a long time because of being busy at work,'' said a woman surnamed Yu who is having dinner with her husband at Haidilao.''The new service gives us a chance to have a dinner together without traveling. I would like to give it a try.''

The video hotpot also helped establish a friendship between waitresses in the two cities.

Zhao Huanhuan, in her 20s, who is specially trained for serving in the video room in Shanghai, developed a friendship with a waitress named Lu Ke in the Beijing branch.

Zhao said excitedly: ''It was too amazing to believe. I'm so interested in using the special room and enjoy serving people there. I also talk about some interesting interactive games with Lu before guests come for dinner''.

Although Lu felt a little bit nervous when she first served in front of the screens, she said the new mode of communication also encouraged her to supply better services for customers.

''It's like a service competition. We saw each other through video and I could learn from Zhao's serving,'' Lu said, adding she will visit Zhao if she goes to Shanghai.

It seems that video hotpot doesn't satisfy everyone's taste, however.

小题1:From the passage we know that ______.

A．the video room service has been open for a long time

B．the video room service has been open in many provinces in China

C．using the video room, you have to pay extra 200 yuan per hour

D．the Video room in Beijing is only designed for six people to use小题2:Haidilao may be the name of ______.

A．a theatre

B．a restaurant

C．a cinema

D．a hotel小题3:Why do many customers choose the video room service?

A．Because the service there is excellent.

B．Because they can have dinner with friends without traveling.

C．Because the food there is delicious.

D．Because the room is large enough for six people.小题4:We can learn from the passage that Zhao Huanhuan ______.

A．enjoys communicating with Lu Ke

B．hasn't met Lu Ke for a long time

C．is twenty years old now

D．learned a lot from Lu Ke小题5:What do you suppose will be talked about in the paragraph to be followed?

A．Lu's visit to Zhao in Shanghai.

B．Other customers' praise for the service.

C．How to improve the service.

D．Other customers' complaint about the service.

一级保养由生产班组工人交接时进行，停机时间为（）小时

A.1～2

B.0.5

C.0.25

D.2～3