反转恢复脉冲序列，施加的第一个脉冲是（） A.180° B.90° C.270° D

阅读理解。

     Winter is a time for many exciting sports: sledding (雪橇), skating and skiing. Skating and skiing needs

lots of skills (技巧). Sledding gives you good exercise and is lots of fun!

     A sled looks like a boat. It can move easily over snow or ice. Early sleds were made of wood. Now

some better sleds are made of glass.

     Sleds can be pulled by animals. In some very cold parts of the world, people make animals like dogs,

horses, and reindeer (驯鹿) pull goods or people in sleds.

      People also sled for sports and fun. Driving a sled does not need much skill. The driver gives a kick

(踢) in the snow to start the sled. He or she can also ask someone else for help. In a sled, there can be one

person or several.

      Usually, you have to lie on your back, feet first in a sled. As you travel, you move your body and feet

to keep it in the right direction (方向). 

      There is a special sled called the skeleton sled (骨架雪橇). It's very different.

      On a skeleton, you lie on your stomach and drive the sled in a head-first way. It is very fast! Many

are afraid to ride it. But once they try it they want to do it again!

阅读短文，回答下列问题：

1. What are sleds made of?

2. What kind of animals can pull sleds?

3. What are sleds used for? 

4. How do people sled? Describe the process.

5. What is a skeleton sled like?  

《荷塘月色》一文中引用《采莲赋》《西洲曲》有什么深意？

 ______________________________________________________

最合适泵送的混凝土坍落度是（ ）

A．20mm

B．50mm

C．80mm

D．100mm

下列措施中，对于预防牛海绵状脑病及人类克雅病无效的是（）。

A.不用动物组织饲料喂养动物 

B.对可疑动物尸体进行焚化或高压消毒132℃持续1小时 

C.1M氢氧化钠60分钟浸泡染病动物尸体 

D.严格遵守消毒程序，使用一次性神经外科器械 

E.手术器械苯扎溴胺浸泡

信息系统工程建设过程比较复杂，涉及基础设施、网络、软件开发、系统集成等各个方面。下列叙述中，不正确的是______。

A．由于信息系统工程属于典型的多学科合作项目，因此承建单位除了要有IT方面的技术外，还要有行业应用方面的丰富经验
B．信息系统工程可以采用软件复用技术，因此能够按标准化快速开发完成
C．信息系统工程行业特征比较明显，行业差异比较大
D．信息系统工程在逐渐明晰的过程中产生很多变更，意味着工作范围可能发生改变