下列说法中，发生了化学变化的是 [ ] A．用食醋除水壶中的水垢 B．用木炭除中

m为何值时，f（x）=x²+2mx+3m+4

（1）有且仅有一个零点

（2）有两个零点且均比-1大．

给出下列实数：－3.14，，，，0.121121112…（相邻两个2之间依次增加一个1）其中无理数的个数为                                    （     ）

A．1

B．2　　

C．3　

D．4

Try and see inside your mind a wide open blue sky and a wide green sea far away. Breathe in as you circle your hands high above your head, then bend back a little. Breathe out as you circle your arms back down to your sides..."

Following the yoga teacher's gentle instructions, Bai Yunuo,15, from the High School attached to Beijing Normal University tried to get each of her poses correct.

Bai's school offered 24 elective courses (选修课) for Senor 1 students this term and she chose two. It was her first yoga class.

"I'm happy that I can learn yoga at school. I love dancing but I had some injuries on my knees when I was a kid. So I decide to try something soft. Simply stretching into different poses makes me feel free and quiet. And the music is quite comforting. The class is relaxing after a whole day's work," Bai said.

Liu Zehao,15, found his interest was Junior Achievement (企业经营模拟). The course brought students into the real world of business. In their first class, Liu and his group members named their company "Vision". Liu was elected as CEO of the company.

"Here we learn to think like an adult. We have to make our company get more money. It's new and different from other courses," he said.

Liu and Bai take their elective courses twice a week with students from other classes who share the same interest. The students will get two credits (学分) from each course at the end of this term. They have to achieve eight credit points from electives to graduate from high school.

If you are interested in more about elective courses, please CLICK HERE to register for general elective courses.

小题1: What’s the main idea of the first paragraph?

A．Skills for imagination.

B．Learning tips.

C．Instruction for yoga students.

D．Breathing rules.小题2:What can be inferred from the passage?

A．Bai does not like dancing.

B．Yoga is softer than dancing.

C．Students study hard for credits.

D．The elective courses are easy.小题3: Which of the sentence is NOT true about Liu Zehao?

A．He was interested in Junior Achievement which brought him the real world of business.

B．He was elected as CEO of the company named "Vision".

C．He was an adult and he tried to make more money for his company.

D．He took their Junior Achievement twice a week.小题4:Where can you possibly find this passage?

A．A textbook

B．A newspaper

C．A magazine

D．The internet

图2-11是生物接触氧化处理技术二段式处理流程，图中1、2、3、4、5分别代表（）。

A．初次沉淀池、一段接触氧化、中间沉淀池、二段接触氧化、二次沉淀池

B．沉砂池、一段接触氧化、中间沉淀池、二段接触氧化、二次沉淀池

C．初次沉淀池、一段接触氧化、曝气池、二段接触氧化、二次沉淀池

D．初次沉淀池、一段接触氧化、沉淀池、二段接触氧化、清水收集池

运营商是“互联网+”发展的中流砥柱，体现在（）

A.运营商建设的宽带网络是“互联网+”发展的根本

B.运营商打造的基础资源是“互联网+”发展的基石

C.运营商提供的服务能力是“互联网+”发展的依托

D.运营商承担的信息安全是“互联网+”发展的保障