To speed （） your entry, please bring your

“凯式定氮法”是通过测奶品中含氮量（氮元素的质量分数）来折算奶品中蛋白质含量的一种方法。为了提高氮的含量，不法分子将三聚氰胺（化学是为C₃H₆N₆）添加进奶品中，冒充蛋白质，使许多婴幼儿长期服用后产生结石，严重影响婴幼儿的健康。不法分子如果向1000g牛奶中添加2.52g三聚氰胺，能够冒充蛋白质的质量为（已知蛋白质中所含氮元素的质量分数约为16%）

A．2.52g

B．4. 44g

C．10.5g

D．12.32g

出生后，血液淋巴细胞和中性粒细胞数基本相等的第2次交叉时间在（）

A.2～2.5岁

B.2.5～3岁

C.3～4岁

D.4～5岁

E.6～7岁

钢轨探伤车计算机系统的操作步骤为：首先在SCC计算机键入go回车，再在显示计算机键入go回车，然后在SCC计算机上敲任意键。

阅读理解。

     One day an old woman was traveling alone in the mountains. Suddenly she saw something shining in the

stream. When she came close, she found it was a precious stone. She put the stone into her bag and went on

with her trip.

     The next day the old woman met a young man, who was also a traveler in the mountains. The young man

looked very hungry, so the old woman opened her bag to share her food. The hungry traveler saw the precious

stone and asked carefully, "The stone is beautiful. Would you like to give it to me?"

     "Sure. Why not?" the woman said, and handed the stone to him.

     The young man left happily with the stone. He knew it was worth enough to give him security for a lifetime.

But a few days later he came back to return the stone to the woman.

     "I've been thinking," he said. "I know how valuable the stone is, but I give it back and hope that you can give

me something even more precious. Give me what you have within your bag."

     The woman opened her bag. It was almost empty. She looked at the young man and smiled, "I have nothing

special in my bag, but I do have something precious-the joy of giving!"

     The young man felt ashamed and left silently.

1. How did the young man find the precious stone? [ ]

A. He found it in his food.

B. He dug it out in a valley.

C. He saw it in the woman's bag.

D. He noticed it shining in the stream.

2. What does the underlined word "security" in Paragraph 4 probably mean? [ ]

A. Money.

B. Worry.

C. Health.

D. Trouble.

3. The man returned the stone to the woman because _____. [ ]

A. he found the stone was not precious

B. he understood the real meaning of joy

C. he felt embarrassed at taking away the stone

D. he wanted to get something even more precious

4. Which of the following would be the best title of the passage? [ ]

A. A special stone

B. The joy of giving

C. A woman and a young man

D. An experience in the mountains

在UNIX系统中，一个命令的执行会花费一些时间，为了避免等待，可采用

A．后台命令

B．输入重定向

C．输出重定向

D．管道命令