普通钻床，根据其结构和适用范围不同可分为台钻、立钻和摇臂钻三种。

“低碳经济”是近年国际社会应对人类大量消耗石化能源、大量排放二氧化碳引起全球气候灾害性变化而提出的新概念，在我国，大力提倡“低碳经济”有助于

①引导人们树立正确的消费观念，实施绿色消费，有助于形成新的节能生活方式

②切实转变经济发展方式

③贯彻落实科学发展观

④降低企业生产成本，提高经济效益

A．①③④

B．①②④

C．①②③

D．②③④

阅读理解。

     More teachers are starting off the school year with letters to parents and students to introduce themselves

and set a tone (基调)for the year. The letters are a good way to start positive communication with parents,

several teachers told Education World.

     "I think it's professional (专业的)," said Dorothy Peselli, an English teacher at Sparta

High School in Sparta, New Jersay, Peselli, who gives out the letters the first day of school,

told Education World."It gives parents an image of you as a professional. If you start

communication off in a positive manner, you will have the parents on your side when you need them."

     In her letter to parents, Peselli encourages them to call or e-mail her with specific concerns about their

children."I want to work as a team to make sure that your child becomes an independent lifelong learner,"

Peselli wrote to parents last September. She also telephones the parents of all her students at the beginning of

the year.

     Peselli includes with the letter a classroom handbook (手册) listing plans and rules. And she requires that

both parents and students read and sign statements (included in the letter!) that they read the handbook. The

student letter also lists needed supplies and gives encouragement."Please come to class ready to work and learn.

This will be an exciting year for all of us," it  says.

      Last year, Peselli taught at a different high school and parents there were"shocked", but appreciative, that

she had so much contact with them,"I received roses and a thank-you note from one boy and his mother".

Peselli said. She wished her own children's teachers would take the time to write notes as well."I never got a

letter home from any of my daughter's high school teachers." She said. "It would be nice to know the

background of some of the people who are teaching my daughter."

1. We may learn from the text that ____.

A. most teachers are writing letters to parents and students

B. the handbook is used to list supplies and give encouragement

C. Peselli believe it important for teachers to exchange information with parents

D. Peselli mainly introduces her background and teaching experiences in the letters

2. The underlined word"it" in the fourth paragraph refers to _____. 

A. the handbook B. the requirement C. the school D. the letter

3. We can infer from the last paragraph that _____.

A. parents were satisfied with Peselli's way of working

B. Peselli means to surprise parents by writing students

C.Peselli seemed to be popular among boy students

D. all Peselli's children are studying in high schools

4. The purpose of the text is to _____.

A. introduce an English teaching method

B. give advice on how to teach students

C. encourage teachers to keep in touch with parents

D. show us how Dorothy Peselli makes teaching plans

水占人体总重量的（）。

A.50-60%

B.50-55%

C.50-70%

D.60-70%

建设单位，设计单位，施工单位，工程监理违法国家规定，降低工程质量，造成重大安全事故的，对直接责任人处3年以下有期徒刑或拘役，并处罚金.

关于驼背运输的挂车列车的形式说法正确的有______。

A．挂车列车是一种公路和铁路两用的挂车

B．这种公铁两用挂车在公路上用自己的轮子挂在公路拖车后面行驶

C．到达火车站，将其在公路上行驶时使用的轮子收起来，放上火车轮架，就可以在铁轨上行驶

D．到达目的地后，又可以还原成公路运输工具，用公路挂车将其运到指定的仓库

E．到达目的地后，又可以还原成公路运输工具，用公路拖车将其运到指定的仓库