贷款人从事项目融资业务，评估项目风险时应当以（ ）为核心：A.偿债能力分析 B.

如图所示，用半径为0.4m的电动滚轮在长薄铁板上表面压轧一道浅槽．薄铁板的长为2.8m、质量为10kg．已知滚轮与铁板、铁板与工作台面间的动摩擦因数分别为0.3和0.1．铁板从一端放入工作台的滚轮下，工作时滚轮对铁板产生恒定的竖直向下的压力为100N，在滚轮的摩擦作用下铁板由静止向前运动并被压轧出一浅槽．已知滚轮转动的角速度恒为5rad/s，g取10m/s²．

（1）通过分析计算，说明铁板将如何运动？

（2）加工一块铁板需要多少时间？

（3）加工一块铁板电动机要消耗多少电能？

下列有关实验原理或操作不正确的是（　　）

A．镀锌铁皮镀锌层厚度的测定：用1：4的硫酸溶液与镀锌铁皮反应，当产生的氢气速率明显减慢时，锌镀层完全反应

B．乙醇与浓硫酸共热至170℃，将制得的气体通入酸性KMnO₄溶液来检验制得气体是否为乙烯

C．阿司匹林的提纯是将粗产品先溶解在饱和碳酸氢钠溶液中，过滤后向滤液加入盐酸，冷却后有晶体析出，抽滤并用少量的冷水洗涤晶体

D．用盐酸检验牙膏中的摩擦剂是SiO₂、CaCO₃、Ca₃（PO₄）₂中的哪一种

在细胞膜蛋白质"帮助"下物质通过膜顺浓度梯度或电位梯度转运的方式是（）

A.出胞作用

B.主动转运

C.单纯扩散

D.易化扩散

E.吞噬作用

关于联合体各方在中标后承担的连带责任，下列说法错误的是( )。

A．中标的联合体除不可抗力外，不履行与招标人签订的合同时，履约保证金不予退还
B．联合体在接到中标通知书未与招标人签订合同前，除不可抗力外，联合体放弃中标项目的，其已提交的投标保证金不予退还
C．联合体在接到中标通知书未与招标人签订合同前，除不可抗力外，联合放弃中标项目的，给招标人造成的损失超过投标保证金数额的，应当对超过部分承担连带赔偿责任
D．联合体在接到中标通知书未与招标人签订合同前放弃中标项目的，其已提交的投标保证金应予以退还

Many people are surprised when they find the Internet(因特网)was set up in the 1960s. At that time, computers were large and expensive. Computer networks(网络) didn’t work well. If one computer in the network broke down, then the whole network stopped. So a new network system (系统) had to be set up. It should be good enough to be used by many different computers. If a part of the network was not working, information could be sent through another part. In this way computer network system would keep on working all the time.
At first the Internet was only used by the government, but in the early 1970s,universities(大学) ,hospitals and banks were allowed(允许) to use it too. However, computers were still very expensive and the Internet was difficult to use. By the start of the 1990s, computers became cheaper and easier to use.
Today it is easy to get on-line(上网) and it is said that millions of people use the Internet every day. Sending e-mail is more and more popular among students.
The Internet has now become one of the most important parts of people’s life.

Computers become cheaper and easier to use in the ______.

A. 1960s


B. 1970s

C. 1990s