传染病的预防包括（） A.改善卫生条件和免疫预防 B.改善卫生条件、免疫预防和健康教

2g Cu₂S和CuS的混合物在酸性溶液中用400mL 0.075mol/L KMnO₄溶液处理，发生反应如下：

8MnO₄^－＋5Cu₂S＋44H^＋＝10Cu^2＋＋5SO₂＋8Mn^2＋＋22H₂O

6MnO₄^－＋5CuS＋28H^＋＝5Cu^2＋＋5SO₂＋6Mn^2＋＋14H₂O

反应后煮沸溶液，赶尽SO₂，剩余的KMnO₄恰好与350mL 0.1mol/L(NH₄)₂Fe(SO₄)₂溶液完全反应。

（1）配平KMnO₄与(NH₄)₂Fe(SO₄)₂反应的离子方程式：

   MnO₄^－＋   Fe^2＋＋   H^＋＝   Mn^2＋＋   Fe³⁺＋H₂O

（2）KMnO₄溶液与混合物反应后，剩余KMnO₄的物质的量为　　　　　mol。

（3）欲配制500mL 0.1mol/L Fe^2＋溶液，需称取(NH₄)₂Fe(SO₄)₂·6H₂O（M＝392g/mol）的质量为         g。

（4）混合物中Cu₂S的质量分数为                。

根据对话内容，从方框内的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

A:     小题1:   ?

B: I want to buy a miracle.

A:     小题2:  ?

B: It’s for my little brother. He has something bad growing inside his head. My daddy said only a miracle could save him.    小题3:   ?

A: How much do you have with you?

B: Two dollars and twelve cents. If it’s not enough, I can get some more later.    小题4:  .

A: What kind of miracle does your brother need?

B:    小题5: . He needs an operation. But my daddy can’t pay for it. So I’ve brought all my savings to buy a miracle to save him.

A: Ok, little girl. It’s the exact price of a miracle for your brother. Leave your address and the miracle will be delivered to your house.

(Some days later, enough money was raised to help the family. The operation was done and the little girl’s brother was saved. So how much is a miracle? It’s two dollars and twelve cents plus faith and love. )

要容易看出各种数量的多少及增减变化的情况应绘制折线统计图．______．

下面哪个算式是正确的．（　　）

A．92+22+78=92+100

B．102×56=100×56+2

C．97+3×12=100×12

D．35×16=35×2+35×8

对于一个没有先例的工程或工程内容及其技术经济指标尚未全面确定的新项目一般采用( )、

A．固定总价合同

B．可调总价合同

C．估算工程量单价合同

D．成本加酬金合同