“滚滚长江东逝水，浪花淘尽英雄。”这是四大名著（）的开篇词。

计划生育药具信息系统管理员的工作职责是什么？

风湿热最严重的临床表现是（）

A.关节炎

B.舞蹈病

C.皮下结节

D.环形红斑

E.心脏炎

全面的风险管理模式强调信用风险、()和操作风险并举，组织流程再造与技术手段创新并举。

A.市场风险

B.流动风险

C.战略风险

D.法律风险

Living in a modern society with more and more out-of-date but still useful computers, many people have to face such a troubling problem: How to deal with those old computers? Some old ones are put away in homes. Many more are just thrown out with the rubbish.

Don’t worry! Some companies are coming up with new ways to cut the number of old computers. Sony, Dell, Hewlett-Packard and other companies now agree to take back some old computers.

In some countries, there are laws about what to do with old computers. By law, computer companies will have to pay for collecting and recycling their used products. And 70% of computer waste must be recycled. The idea behind the laws is that computer companies themselves should pay the cost. That will encourage them to make computers that are easier and cheaper to repair and upgrade（升级）.

While many people are throwing away good computers, others cannot afford them at all. Hundreds of organizations（组织）are working to solve this problem. They collect and repair old computers before sending them to schools, charities（慈善团体）and people who need them. In this way, we can turn one person's rubbish into someone else's useful things-and cut down on waste.

小题1:What do many people do with old computers?

A．They sell them to others.

B．They try to repair them.

C．They give them to others.

D．They stop using them小题2:According to laws in some countries mentioned in the passage, computer companies must_____.

A．recycle most of their products

B．make their computers cheaper

C．repair and upgrade old computers

D．collect all their used products小题3:The last paragraph mainly tells us that hundreds of organizations are working to _________.

A．help the computer companies to collect old ones

B．repair old ones and send them to whoever needs them.

C．advise people not to throw away good computers.

D．encourage people to turn rubbish into useful things.小题4:What is the main idea of this passage?

A．How to repair old computers.

B．Avoid producing too many computers.

C．Encourage to recycle old computers.

D．How to turn rubbish into useful things

某硫酸工厂的酸性废水中砷（As）元素含量极高，为控制砷的排放，采用化学沉降法处理含砷废水，工艺流程如下：

相关数据如下表，请回答以下问题：

表1．几种盐的K_sp

表2．工厂污染物排放浓度及允许排放标准

（1）该硫酸工厂排放的废水中硫酸的物质的量浓度c(H₂SO₄)=           mol·L^－1。

（2）若酸性废水中Fe³⁺的浓度为1.0×10^－4mol·L^－1，c(AsO₄^3－)=          mol·L^－1。

（3）工厂排放出的酸性废水中的三价砷（H₃AsO₃弱酸）不易沉降，可投入MnO₂先将其氧化成五价砷（H₃AsO₄弱酸），MnO₂被还原为Mn^2＋，反应的离子方程式为                                             。

（4）在处理含砷废水时采用分段式，先向废水中投入生石灰调节pH到2，再投入生石灰将pH调节到8左右使五价砷以Ca₃(AsO₄)₂形式沉降。

①将pH调节到2时废水中有大量沉淀产生，沉淀主要成分的化学式为             ；

②Ca₃(AsO₄)₂在pH调节到8左右才开始沉淀，原因为                               

                                                                           。

③砷酸（H₃AsO₄）分步电离的平衡常数(25℃)为：K₁=5.6×10^－3 K₂=1.7×10^－7 K₃=4.0×10^－12，第三步电离的平衡常数的表达式为K₃=                           。Na₃AsO₄的第一步水解的离子方程式为：AsO₄^3－+H₂OHAsO₄^2－+OH^－，该步水解的平衡常数（25℃）为：                  （保留两位有效数字）。