问题 选择题

某离子晶体晶胞结构如图2-15所示,图中X位于立方体的顶点,Y位于立方体中心.晶体中距离最近的2个X与一个Y形成的夹角∠XYX的角度为  (   )

A.109°28′

B.107°18′

C.90°

D.120

答案

答案:A

题目分析:根据结构图可知,4个X构成正四面体型,所以2个X与一个Y形成的夹角∠XYX的角度为109°28′,答案选A。

点评:该题是高考中的常见题型,属于中等难度试题的考查,试题基础性强,侧重对学生能力的培养和训练,有利于培养学生的逻辑推理能力和空间想象能力,提高学生的应试能力。

阅读理解

We have met the enemy and he is ours We bought him at a pet shop. When monkey-pox, a disease usually found in the African rain forest suddenly turns up in children in the American .Midwest it’s hard not to wonder of the disease that comes from foreign animals is homing in on human beings. “Most of the infections (感染)we think of as human infections started in other animals “ says Stephen Morse director of the Center for Public Health Preparedness at Columbia University.

It’s not just that we’re going to where the animals are; we’re also bringing them closer to us Popular foreign pets have brought a whole new disease to this country A strange illness killed Isaksen’s pets and she now thinks that keeping foreign pets is a bad idea “I don’t think it’s fair to have them as pets when we have such a limited knowledge of them “says Isaksen

“Laws allowing these animals to be brought in from deep forest areas without stricter control need changing “says Peter Schantz Monkey-pox may be the wake-up call. Researchers believe infected animals may infect their owners. We know very little about these new diseases A new bug(病毒)may be kind at first. But it may develop into something harmful(有害的)Monkey-pox doesn’t look a major infectious disease But is not impossible to pass the disease from person to person

小题1:We learn from Paragraph I that the pet sold at the shop may_______.

A.come from Columbia

B.prevent us from being infected

C.enjoy being with children

D.suffer from monkey-pox小题2:Why did Isaksen advise people not to have foreign pets?

A.They attack human beings

B.We need to study native animals

C.They can’t live out of the rain forest

D.We do not know much about them yet小题3:What does she phrase “the wake-up call” in paragraph 3 most probably mean?

A.a new disease

B.a clear warning

C.a dangerous animal

D.a morning call小题4:The text suggests that in the future we               .

A.may have to fight against more new diseases

B.may easily get infected by diseases from dogs

C.should not be allowed to have pets

D.should stop buying pests from Africa

判断题