纸币的出现给经济流通带来了更多的便捷，下图是世界上最早的纸币_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

纸币的出现给经济流通带来了更多的便捷，下图是世界上最早的纸币，它出现于

[ ]

A．唐朝

B．北宋

C．南宋

D．元朝

答案

答案：B

写作题

根据表格信息写一封信，把讨论的情况汇报给编辑，并说出建动物园的看法。(60字左右)

Pros	Cons	Your ideas
Zoos are like living textbooks.	Animals are kept in the tiny cages.
Zoos provide homes for endangered animals.	Animals can hardly move at all.
They educate the public about caring for them.	Animals are only given food once a day.
…	…

Dear Editor:
Today we had a dicussion of whether we need to build zoos to portcect the endangered animals. Some
students think we should build zoos______________________________________________________________________________________________________________________________________

多项选择题

下列叙述中正确的是（）。

A．孔隙率与密实度两者乘积为1

B．软化系数越小则材料耐水性越差

C．材料吸湿性大小，用孔隙率表示

D．材料渗透系数越大，则抗渗性越强

E．比强度是衡量材料轻质高强的指标