如果只在第二、四节课使用投影机，那么第三节课应关闭一下使其休息。

决定CT机连续工作时间长短的机器性能指标是（）

A.磁盘容量

B.电源容量

C.X线管热容量

D.X线管焦点大小

E.扫描时间

胃内最易出现溃疡的部位在（）。

A.胃底

B.胃体大弯侧

C.幽门管

D.胃角

E.胃窦

Reading is not the only way to gain knowledge of the work in the past. There is another large reservoir (知识库) which may be called experience, and the college students will find that every craftsman (工匠) has something he can teach and will generally teach gladly to any college student who does not look down upon them. The information from them differs from that in textbooks and papers chiefly in that its theoretical (理论的) part -- the explanations of why things happen -- is frequently quite fantastic (神奇的) . But the demonstration (示范) and report of what happens, and how it happens are correct even if the reports are in completely unscientific terms. Presently the college students will learn, in this case also, what to accept and what to reject. One important thing for a college student to remember is that if Aristotle could talk to the fisherman, so can he.

　　Another source of knowledge is the vast store of traditional practices handed down from father to son , or mother to daughter, of old country customs ,of folklore (风俗). All this is very difficult for a college student to examine, for much knowledge and personal experience is needed here to separate good plants from wild grass.The college students should learn to realize and remember how much of real value science has found in this wide, confused wilderness and how often scientific discoveries of what had existed in this area long age.

小题1: In the last paragraph the phrase "this wide, confused wilderness" refers to _____.

A．personal experience

B．wild weeds among good plants

C．the information from the parents

D．the vast store of traditional practices小题2: Which of the following statements is supported by the passage?

A．The college students have trouble separating good plants from wild grass

B．Craftsman’s experience is usually unscientific

C．The contemptuous (傲慢的) college students will receive nothing from craftsmen

D．Traditional practices are as important as experience for the college students小题3: The author advises the college students to ______ .

A．be contemptuous to the craftsman

B．be patient in helping the craftsman with scientific terms

C．learn the craftsman’s experience by judging it carefully

D．gain the craftsman’s experience without rejection小题4: The main idea of this passage is about ________.

A．what to learn from the parents

B．how to gain knowledge

C．why to learn from craftsman

D．how to deal with experience

装置停净化风后，风开型调节阀改为（）控制。

A、上游阀

B、下游阀

C、副线阀

D、调节阀

火灾发生的几个阶段，在哪个阶段灭火时机和效果最佳？