曲轴扭转疲劳破坏还会因扭转产生()造成。A.过大扭转应力 B.过大振动 C.过大扭转

题型:单项选择题

问题:

曲轴扭转疲劳破坏还会因扭转产生()造成。

A.过大扭转应力

B.过大振动

C.过大扭转应力集中系数

D.过大附加扭转应力

考点:海船船员考试船机零件的疲劳破坏船机零件的疲劳破坏题库
题型:单项选择题

已知果蝇刚毛和截毛这对相对性状由X和Y染色体上一对等位基因控制,刚毛(B)对截毛(b)为显性;控制果蝇的红眼和白眼这对性状的基因只存在于X染色体上,红眼(R)对白眼(r)为显性(如下图所示)。

(1)若只考虑刚毛和截毛这对相对性状的遗传:

①.果蝇种群中雄果蝇的基因型除了有XBYB和XBYb外,还有______________。

②.现将两只刚毛果蝇杂交,子代雌果蝇中既有刚毛,又有截毛,雄果蝇全为刚毛,则这两只果蝇的基因型是_____________。在研究统计子代时发现有一只XXY的截毛果蝇,分析其变异是由于形成配子时发生的。

③.该变异发生在_________(雌果蝇或雄果蝇)的__________(时期)。

(2)种群中有各种性状的雌果蝇,现有一只红眼刚毛雄果蝇(XR_Y_),要通过一次杂交实验判断它的基因型,应选择表现型为____________的雌果蝇与该只果蝇交配,然后观察子代的性状表现。

①.如果子代果蝇均为刚毛,则该雄果蝇基因型为XRBYB

②.如果子代______________________________________;

③.如果子代______________________________________。

题型:单项选择题

25岁初产妇,妊娠38周,规律宫缩12小时,自然破膜8小时,宫口开大3cm,胎心110次/分,胎心监护有多个晚期减速出现。本例正确处置应是

A.急查尿雌激素/肌酐比值

B.吸氧,严密观察产程进展

C.静注25%葡萄糖液内加维生素C

D.静脉滴注缩宫紊,加速产程

E.立即行剖宫产术

题型:单项选择题

A land free from destruction, plus wealth, natural resources, and labor supply—all these were important 1 in helping England to become the center for the Industrial Revolution. 2 they were not enough. Something 3 was needed to start the industrial process. That "something special" was men—4 individuals who could invent machines, find new 5 of power, and establish business organizations to reshape society.

  The men who 6 the machines of the Industrial Revolution 7 from many backgrounds and many occupations. Many of them were 8 inventors than scientists. A man who is a 9 scientist is primarily interested in doing his research 10 .He is not necessarily working 11 that his findings can be used.

  An inventor or one interested in applied science is 12 trying to make something that has a concrete use. He may try to solve a problem by 13 the theories 14 science or by experimenting through trial and error. Regardless of his method, he is working to obtain a 15 result: the construction of a harvesting machine, the burning of a light bulb, or one of 16 other objectives.

  Most of the people who 17 the machines of the Industrial Revolution were inventors, not trained scientists. A few were both scientists and inventors. Even those who had 18 or no training in science might not have made their inventions 19 a groundwork had not been laid by scientists years 20 .

  1.A.cases      B .reasons            C .factors           D .situations

  2.A.But        B .And             C .Besides          D .Even

  3.A.else       B .near               C .extra            D .similar

  4.A.generating  B .effective          C .motivating        D .creative

  5.A.origins      B .sources          C .bases             D .discoveries

  6.A.employed   B .created            C .operated          D .controlled

  7.A.came       B .arrived            C .stemmed         D .appeared

  8.A.less       B .better             C. more            D .worse

  9.A.genuine     B .practical           C .pure            D .clever

  10.A.happily    B .occasionally        C. reluctantly        D .accurately

  11.A.now      B .and                C .all              D .so

  12.A.seldom    B .sometimes         C .all                D .never

  13.A.planning  B .using              C .idea               D .means

  14.A.of       B .with              C .to                 D .as

  15.A.single     B .sole              C. specialized         D .specific

  16.A.few      B .those              C .many              D .all

  17.A.proposed  B .developed         C .supplied           D .offered

  18.A.little      B .much             C .some             D .any

  19.A.as        B .if               C .because           D .while

  20.A.ago      B .past               C .ahead              D .before

题型:单项选择题

滑压除氧系统只能应用于()机组。

A、单元制;

B、母管制;

C、扩大单元制;

D、母管制或单元制。

题型:单项选择题

简述人员促销的种类和步骤。

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