X控制图的上、下控制界限UCL和LCL值，理论上应为（）。 A．UCL=TVLUL=

Family traditions were important in our house, and none was more appreciated than the perfect Christmas tree.

“Dad, can we watch when you trim(修剪) the tree?” My eldest son, Dan, nine, and his seven-year-old brother John, asked.

“I won’t be cutting this year,” my husband Bob said. “Dan, you and John are old enough to measure things. Do it all by yourselves. Think you boys can handle it?”

Dan and John seemed to grow six inches in their chairs at the thought of such an amazing responsibility. “We can handle it,” Dan promised. “We won’t let you down.”

A few days before Christmas, Dan and John rushed in after school. They gathered the tools they’d need and brought them out to the yard, where the tree waited. I was cooking when I heard the happy sounds as the boys carried the tree into the living room. Then I heard the sound that every mother knows is trouble: dead silence. I hurried out to them. The tree was cut too short. John crossed his arms tight across his chest. His eyes filled with angry tears.

I felt worried. The tree was central to our holiday. I didn’t want the boys to feel ashamed every time they looked at it. I couldn’t lower the ceiling, and I couldn’t raise the floor either. There was no way to undo the damage done. Suddenly, a thought came to my mind, which turned the problem into the solution.

“We can’t make the tree taller,” I said. “But we can put it on a higher position.”

Dan nodded his head sideways. “We could put it on the coffee table. It just might work! Let’s try it!”

When Bob got home and looked at the big tree on top of the coffee table, Dan and John held their breath.

“What a good idea!” he declared. “Why didn’t I ever think of such a thing?”

John broke into a grin. Dan’s chest swelled with pride.

小题1:The underlined part “grow six inches” (Para. 4) implies the brothers felt        .

A．proud

B．nervous

C．embarrassed

D．Scared小题2:What happened after the brothers moved the Christmas tree into the living room?

A．They rushed to school.

B．They began to decorate the tree.

C．They got angry with each other.

D．They found the tree was cut short.小题3:How could the short tree be turned into a perfect one?

A．By making the tree taller.

B．By lowering the ceiling.

C．By placing it on a coffee table.

D．By raising the floor.小题4:What Bob said in the last but one paragraph showed        .

A．he was a little disappointed

B．he was too stupid to think of the idea

C．he appreciated what the brothers had done

D．he should not have given them the task

小李同学测得50mL酒精和50mL水混合在一起后的体积小于100mL．这个事实说明（　　）

A．酒精分子和水分子之间都有空隙

B．酒精分子和水分子质量很小

C．酒精和水发生了分解反应

D．酒精分子和水分子都变成了原子

工业上为了处理含有Cr₂O₇^2－酸性工业废水，采用下面的处理方法：往工业废水中加入适量的NaCl，以Fe为电极进行电解，经过一段时间，有Cr(OH)₃和Fe(OH)₃沉淀生成，工业废水中铬（Cr）的含量已低于排放标准。请回答下列问题：

（1）电极反应式：阳极___________，阴极_____________

（2）写出Cr₂O₇^2－变为Cr³⁺的离子方程式______________

（3）工业废水pH升高的原因_________________________

（4）____（填“能”或“不能”）改用石墨电极，原因______________

在编制预算定额时，对于那些常用的、主要的、价值量大的项目，分项工程划分宜细；次要的、不常用的、价值量相对较小的项目则可以放粗，这符合预算定额编制的( )原则。

A．平均先进性
B．时效性
C．保密
D．简明适用

H级K型热电偶的测温范围为400℃以上，其允许误差为（）。

A.±3℃

B.0.4%t℃

C.±0.75%t℃