离心泵输不出液体的原因有那些?
参考答案:
1)开泵前注入液体不够;2)泵或吸入管线存气或者漏气;3)吸入高度超过泵的允许范围;4)管道阻力过大;5)泵或管道内有异物堵塞。
由于工作的调动,小明随父母来到了上海这个陌生的城市,由于环境的陌生,加上语言的障碍,小明不爱和同学交流,也不爱跟老师沟通,成绩一落千丈,常常受到老师的批评,经常逃课,通宵上网,逛酒吧等,父母也手足无措,于是向社会工作者小张求助,小张在分析小明的问题时,应该关心的环境问题有()。
A.大众传媒
B.朋辈群体
C.家庭环境
D.学校氛围
E.社区文化
In every cultivated language there are two great classes of words which, taken together, comprises the whole vocabulary. First, there are those words (1) which we become acquainted in daily conversation, which we (2) , that is to say, from the (3) of our own family and from our familiar associates, and (4) we should know and use (5) we could not read or write. They (6) the common things of life, and are the stock in trade of all who (7) the language. Such words may be called "popular", since they belong to the people (8) and are not the exclusive (9) of a limited class.
On the other hand, our language (10) a multitude of words which are comparatively (11) used in ordinary conversation. Their meanings are known to every educated person, but there is little (12) to use them at home or in the market-place. Our (13) acquaintance with them comes not from our mother’s (14) or from the talk of our school-mates, (15) from books that we read, lectures that we (16) , or the more (17) conversation of highly educated speakers who are discussing some particular (18) in a style appropriately elevated above the habitual (19) of everyday life. Such words are called "learned", and the (20) between them and the "popular" words is of great importance to a right understanding of linguistic process.
15()
A.besides
B.and
C.or
D.but