紫外线灯管用于空气消毒时，有效距离______________m、照射时间为____

Proper arrangement of classroom space is important to encouraging interaction. Most of us have noticed how important physical setting is to efficiency and comfort in our work. College classroom space should be designed to encourage the activity of critical thinking. We may be approaching the twenty-first century, but step into almost any college classroom and you step back in time at least a hundred years. Desks are normally in straight rows, so students can clearly see the teacher but not all their classmates. The assumption behind such an arrangement is obvious. Everything of importance comes from the teacher.

With a little imagination and effort, unless desks are fixed to the floor, the teacher can correct this situation and create space that encourages interchange among students. In small or standard-size classes, chairs, desks, and tables can be arranged in a variety of ways. The primary goal should be for everyone to be able to see everyone else. Larger classes, particularly those held in lecture halls, unfortunately, allow much less flexibility.

Arrangement of the classroom should also make it easy to divide students into small groups for discussion or problem-solving exercises. Small classes with movable desks and tables present no problem. Even in large lecture halls, it is possible for students to turn around and form groups of four to six. Breaking a class into small groups provides more opportunities for students to interact with each other, think out loud, and see how other students’ thinking processes operate all essential elements in developing new modes of critical thinking. In courses that regularly use a small group format, students might be asked to stay in the same small groups throughout the course. A colleague of mine, John, allows students to move around during the first two weeks, until they find a group they are comfortable with. John then asks them to stay in the same seat, with the same group, from that time on. This not only creates a comfortable setting for interaction but helps him learn students’ names and faces.

The expression "step back in time at least a hundred years" (in Paragraph 1) is intended to convey the idea that ().

A. college classrooms often remind people of their college life

B. critical thinking was encouraged even a century ago

C. a hundred years ago, desk arrangement in a classroom was quite different

D. there is not much change in educational idea over the past hundred years

要求主管人员根据具体的人的不同，灵活采用不同的管理措施，这是管理学的（）

A.科学管理理论

B.权变理论

C.管理过程理论

D.双因素理论

酒精致癌的主要机制是（）。

A.改变组织对致癌物的易感性

B.促进内源性致癌物的产生

C.本身具有致癌作用

D.转运致癌物至其作用部位

E.与癌基因的结构、转录和表达相关

法律关系主体与客体的变更，必然导致( )变更。

A．权利和关系

B．义务和能力

C．内容

D．合同

在施工中应根据（）、机具条件来选择土料，配制泥浆。

A．土料情况

B．施工情况

C．隐患性质

D．泥浆浓度