中国人自己设计和修建的第一条铁路干线是[ ] A．唐胥铁路 B．陇海铁路 C．京

科研文件材料归档范围主要包括哪几个阶段？

按照施工过程中实施见证取样的要求，监理机构中负责见证取样工作韵人员一般为( )。

A．监理员

B．专业监理工程师

C．总监理工程师代表

D．总监理工程师

地下储气库是天然气储存的最佳方式。

任务型读写。阅读下面短文，根据所读内容在表格中的空白处填入恰当的单词。

注意：每个空格只填一个单词。

     A simple water pump is helping to improve the lives of poor families in several Asian and African countries. 

     The treadle pump (脚踏抽水机) is based on a design developed in the 1970s by Norwegian engineer Gunnar

Barnes. It can be made locally and easy to build from bamboo or other wood and two metal cylinders (圆筒)

with pistons (活塞). The pistons go up and down as a person stands on lever (控制杆) devices, treadles, and

uses a natural walking motion.

     How many hours a day the pump needs to be operated depends on the season and how much water is

needed for crops. It could be two hours a day or seven hours a day. Small children sometimes stand with their

parents on the treadles. Everyone in the family can take turns operating the pump.

     Families using them ate more vegetables, because they were able to grow more to eat and to sell. Many of

these families also drank more milk, because they bought a cow with their added earnings. Men with treadle

pumps often no longer have to leave the farm to seek extra work in cities. The pumps can also improve

education. Farmers often use their extra earnings to buy books for their children or to pay for schooling.

     A farmer in Zambia said he hoped to have enough money in three years, to buy a diesel-powered pump.

Then he could grow more crops over a larger area. But the world economic crisis has had an effect on some

farmers. Even some who were able to buy diesel pumps now do not have enough money to buy fuel. So they

are using their treadle pumps again.

维生素C及PP缺乏症引起的出血机制是（）

A.血管壁异常

B.血小板异常

C.复合性止血机制异常

D.凝血异常

E.抗凝及纤维蛋白溶解异常