地块容积率是控制地块开发强度的一项重要指标，是指()A.地块内建筑总面积与地块用地面

若方程2x^2m+3+3y^5n-9=4是关于x，y的二元一次方程，则m²+n²=______．

某小组同学用盐酸和氢氧化钙，对酸和碱的中和反应进行探究．请你参与．

甲同学向装有氢氧化钙溶液的烧杯中加入盐酸，无明显现象．结论：两种物质未发生反应．

乙同学向滴有酚酞的氢氧化钙溶液的试管中慢慢滴加盐酸，溶液由______色变为无色．结论：两种物质发生了反应．反应的化学方程式为______．

大家认为乙的实验证明盐酸与氢氧化钙发生了中和反应．并对甲的实验继续探究．

[提出问题]甲实验后的溶液中有什么溶质？

[作出猜想]猜想一，只有CaCl₂；猜想二有CaCl₂和Ca（OH）₂；猜想三，有CaCl₂和HCl．

[实验探究]为验证猜想，丙同学设计了方案1和方案2，并按方案进行实验．

方案编号	方案1	方案2	方案3
实验操作（分别取少量甲实验后的溶液于试管中）
实验现象	对比标准比色卡：pH＜7	产生白色沉淀
实验结论	溶液中有HCl	溶液中有CaCl2

[实验结论]丙认为猜想三正确．

[实验评价]丙的实验操作和方案中有不足之处，其不足之处是______．

大家讨论后通过方案3即证明了猜想三正确，其实验中应观察到的现象为______．

[实验拓展]为节约资源和避免实验废液对环境污染，小组同学将方案1和方案3及甲实验后烧杯中剩余溶液混合（混合时未见明显现象），并对混合液中的盐分离回收，请将相关内容填入下表．

要分离的盐	所用试剂	主要操作
______	______	______

下列账实核对工作中，应该逐日进行核对的是______。

A．银行存款日记账账面余额与银行对账单的余额是否相符

B．现金日记账账面余额与库存现金额是否相符

C．各项财产物资明细账账面余额与财产物资的实有数额是否相符

D．有关债权债务明细账账面余额与对方单位账面记录是否相符

About ten men in every hundred suffer from color blindness in some way. Women are luckier; only about one in two hundred is affected in this matter. Perhaps, after all, it is safer to be driven by a woman!

There are different forms of color blindness. In some cases a man may not be able to see deep red. He may think that red, orange and yellow are all shadows of green. Sometimes a person cannot tell the difference between blue and green. In rare cases an unlucky man may see everything in shades of green －a strange world indeed.

Color blindness in human beings is a strange thing to explain. In a single eye there are millions of very small things called “cones”. These help us to see in a bright light and to tell difference between colors. There are also millions of “rods”, but these are used for seeing when it is near dark. They show us shape but no color.

Some insects have favorite colors. Mosquitoes prefer blue to yellow. A red light will not attract insects, but a blue lamp will. In a similar way human beings also have favorite colors. Yet we are lucky. With the aid of the cones in our eyes we can see many beautiful colors by day, and with the aid of the rods we can see shapes at night. One day we may even learn more about the invisible colors around us.

1. The passage is mainly about _____________.

A. color and its surprising effects.            B. women being luckier than men

C. danger caused by color blindness          D. color blindness

2. According to the passage, with the help of the “cones”, we can_______________.

A. tell different shapes                    B. see in a weak light

C. kill mosquitoes                        D. tell orange from yellow

3. Why do some people say it is safer to be driven by women?

A. Women are more careful.              B. There are fewer color-blind women

C. Women are fonder of driving than men.    D. Women are weaker but quicker in thinking.

4. Which of the statements about the color- blind is true?

A. Not all of them have the same problem in recognizing color.

B. None of them can see deep red.

C. None of them can tell the difference between blue and green.

D. All of them see everything in shades of green.

5. We can attract and kill mosquitoes by using a _____________.

A. red light       B. yellow light          C. blue light        D. green light

下列不属于破坏性检验的方法是（）

A.煤油试验

B.水压试验

C.氨气试验

D.疲劳试验