佩带自救器撤离危险区域时,如果感到吸气干热且不舒服()。A.可以脱掉口具吸气 B.可

题型:单项选择题

问题:

佩带自救器撤离危险区域时,如果感到吸气干热且不舒服()。

A.可以脱掉口具吸气

B.可以摘掉鼻夹吸气

C.决不可脱掉口具和摘掉鼻夹吸气

考点:煤矿巷修工考试巷修工初级巷修工初级题库
题型:单项选择题
不定项选择
以下关于涡流的说法中,正确的是(   )

A.涡流跟平时常见感应电流一样,都是因为穿过导体的磁通量变化而产生的

B.涡流不是感应电流,而是一种有别于感应电流的特殊电流

C.涡流有热效应,但没有磁效应

D.在硅钢中不能产生涡流

题型:单项选择题

钻削中,切削速度v和进给量f对()的影响是相同的;对钻头的寿命来说切削速度v比进给量,影响大。

A.生产率

B.切削深度

C.表面精度

D.孔精度

题型:单项选择题

Our daily existence is divided into two phases, as distinct as day and night. We call them work and play. We work many hours a day and we allow the necessary minimum for such activities as eating and shopping. 46) The rest we spend in various activities which are known as recreations, an elegant word which disguises the fact that we usually do not even play in our hours of leisure, but spend them in various forms of passive enjoyment or entertainment.

We need to make, therefore, a hard-and-fast distinction not only between work and play but, equally, between active play and passive entertainment. 47) It is, I suppose, the decline of active play — of amateur sport — and the enormous growth of purely receptive entertainment which have given rise to a sociological interest in the problem. If the greater part of the population, instead of indulging in sport, spend their hours of leisure "viewing" television programs, there will inevitably be a decline in health and physique. In addition, we have yet to trace the mental and moral consequences of prolonged diet of sentimental or sensational spectacles on the screen. 48) There is, if we are optimistic, the possibility that the diet is too thin and unnourishing to have much permanent effect on anybody. Nine films out of ten seem to leave absolutely no impression on the mind or imagination of those who have seen them.

49) It is only when entertainment is active, participated in, practiced, that it can properly be called play, and as such it is a natural use of leisure. In that sense play stands in contrast to work, and is usually regarded as an activity that alternates with work.

Work itself is not a single concept. We say quite generally that we work in order to make a living. Some of us work physically, tilling the land, minding the machines, digging the coal; others work mentally, keeping accounts, inventing machines, teaching and preaching, managing and governing. 50) There does not seem to be any factor common to all these diverse occupations, except that they consume our time, and leave us little leisure.

50) There does not seem to be any factor common to all these diverse occupations, except that they consume our time, and leave us little leisure.

题型:单项选择题

以下关于镁过多的临床表现中,错误的是

A.乏力、疲倦
B.腱反射消失
C.血压下降
D.昏迷
E.肌震颤

题型:单项选择题

广播电台,电视台播放他人未发表的作品,不用取得著作权人的许可。

更多题库