噬菌体效价

中性粒细胞减少见于（）

A.流行性出血热

B.伤寒

C.SLK

D.阑尾炎

E.百日咳

第3段文字主要的意思是

A．人们应懂得去欣赏美丽的世界

B．人们除了工作外，对其他事情都不太感兴趣

C．人们为了工作而无暇顾及周围世界的变化

D．美丽的世界对工作繁忙的人而言没有太大意义

公元前138年和公元前119年，汉武帝派谁两次出使西域（）

A.蒙恬

B.张骞

C.班超

D.玄奘

In meditation (冥想), people sit quietly and focus their attention on their breath. As they breathe in and out, they attend to their feelings. As thoughts go through their minds, they let them go. Breathe. Let go. Breathe. Let go.
According to a recent study at the Insight Meditation Society in Barre, Massachusetts, three months of training in this kind of meditation causes a marked change in how the brain allocates (分配) attention. It appears that the ability to let go thoughts that come into mind frees the brain to attend to more rapidly changing things and events in the outside world. Expert mediators are better than other people at catching such fast-changing stimuli(刺激), like facial-expressions.
The study provides evidence for changes in the workings of the brain with mental training. People can learn and improve abilities of all sorts with practice, everything from driving to playing the piano. The study has shown that meditation is good for the brain. It appears to reduce pressure and promote a sense of well-being.
In an experiment, 17 volunteers with no meditation experience in the experimental group spent three months meditating 10 to 12 hours a day. A control group also with no meditation experience meditated for 20 minutes a day over the same period. Both groups were then given the tests with two numbers in a group of letters. As both groups looked for the numbers, their brain activity was recorded.
Everyone could catch the first number. But the brain recordings showed that the less experienced mediators tended to grasp the first number and hang onto it, so they missed the second number. Those with more experience gave less attention to the first number, as if letting it go, which led to an increased ability to grasp the second number. This shows that attention can change with practice.
Just ask Daniel Levision, who meditated for three months as part of the study. "I am a much better listener," he said, "I do not get lost in my own personal reaction to what people are saying. \

The underlined word "them" in Paragraph 1 refers to ______.

A．feelings

B．minds

C．people

D．thoughts

硅酸盐水泥熟料的主要化学成分为（）。

A.CaO、SiO₂、Al₂O₃、Fe₂O₃

B.CaO、SiO₂、Al₂O₃、MgO

C.f-CaO、SiO₂、Al₂O₃、Fe₂O₃