NPT是National (American) Pipe Thread的缩写，属于美国标准的55度锥管螺纹。
NPT是National (American) Pipe Thread的缩写，属于美国标准的55度锥管螺纹。
相关考题：
The origins(起源) of baseball probably stretch back to 1839 when Abner Doubleday, a civil engineering student, laid out a diamond-shaped field at Cooperstown, New York, and attempted to standardize(使标准化) the rules governing the playing of such games as town ball and four old cat, the ancestors(祖先) of baseball. By the end of the Civil War, interest in the game had grown rapidly. Over 200 teams or clubs existed, some of which toured the country playing rivals; they belonged to a national association of Baseball Players that had proclaimed(宣布) a set of standard rules. These teams were amateurs(业余爱好者) or semi-professionals, but as the game waxed in popularity, it offered opportunities for profit, and the first professional team, the Cincinnati Red Stockings, appeared in 1869. Other cities soon fielded professional teams, and in 1876 the present National League was organized chiefly by Albert Spalding. Soon a rival league appeared, the American Association. Competition between the two was intense, and in 1883 they played a post-season(季后赛) contest, the first worlds series. The American Association eventually collapsed, but in 1900 the American League was organized.1. According to the passage, baseball originated in 1839 because ____.A、Abner Doubleday invented a special diamond-shaped pitchB、the rules of earlier games were amalgamated(合并) and regularizedC、civil engineering students became interested in playing gamesD、the old games died out and a new one was needed2. What was different about Baseball Players compared with earlier players?A、They travelled widely.B、They belonged to many clubs.C、They played by agreed rules.D、They were not professional.3. According to the passage, the Cincinnati Red Stockings were formed in 1869 ____.A、because baseball had become more popular by thenB、to enable the amateur players to become professionalC、so that the public had the opportunity to profit from a professional teamD、to produce a means of making money4. From the passage, we understand that the National League was formed in 1876 to ____.A、reorganize the professional teamsB、enable more professional teams to be set upC、to provide a governing authority for baseballD、authorize amateur and professional teams to combine5. According to the passage, at the turn of the century the only remaining baseball organizations were ____.A、the American League and the National LeagueB、the American LeagueC、the American Association and the American LeagueD、the American Association
Questions 61-65 are based on Passage Two:Passage TwoAs the 21st century begins, a number of leaders in politics, education, and other professions believe that the US must adopt some new values to go along with the old traditional ones. What new values should Americans adopt? This is a very difficult question to answer. Certainly, a greater value should be placed on the conservation of natural reasources; Americans should learn to use less and waste less. But conservation has never been a strong value to Americans, who have believed that their country offered an endless,abundant supply of natural resources.Recently, progress has been made-more and more Americans are recycling their paper, cans,bottles,and other goods-but old wasteful habits died hard. Furthermore,the need to protect the environment may conflict with the need for jobs,as in the Northwest ,where conservationists battle lumber companies that want to cut down ancient redwood trees. A belief in the value of conservation is still compared with other American values; it can become stronger only as Americans see the need for it more clearly.In addition,Americans may need to place a strong value on cooperation on a national scale to achieve important national objectives. The American idea of the national good has never been based on national cooperation but rather on the freedom of the individual, maintaining those conditions that provide the greatest freedom and prosperity for the individual .It is far more difficult for Americans to accept shared sacrifice for the common good and wellbeing of the entire country. For example ,although the majority of Americans believe that it is extremely important to balance the national budget and reduce the deficit, they do not want to see cuts in government programs that benefit them personaliy.The American value of competition also hinders the development of a spirit of national cooperation. Competition sometimes encourages feelings of suspicion rather than the mutual trust that is necessary for successful national cooperation. Although Americans often cooperate successfully on the local level-in neighborhood groups and churches, for example, on the national level, they may see themselves as part of an interest group that is competing with other interest groups for government funds. A request by the national government for shared sacrifice may be seen as coercive and destructive rather than voluntary and constructive. However, the demands for the 21st century may compel Americans to place a greater value on national cooperation to solve problems that affect them all, directly and indirectly.The best TITLE of this passage could be ( ).A. Which is Better, New Value or Old Value?B. Conservation vs. Need for JobsC. The Need for New National ValuesD. Cooperation and Competition
What is the basis for the American notion of national good? ( )A. Individual freedom.B. Personal property.C. National cooperation.D. Both A and B.
The author gave an example in the third paragraph in order to( ).A. emphasize the need to place a stronger value on national cooperationB. explain why the American idea has been based on individual freedomC. illustrate the fact that the Americans will not sacrifice their personal interest for the good of the entire countryD. support the idea that Americans need the spirit of national cooperation to achieve important national objectives in the 21st century
Which of the following is NOT true according to the last paragraph?（ ）[A] America will conduct an international-wide aid.[B] The national-wide financial aid is proved helpful.[C] Obama doesn't think highly of American aid system.[D] Mr. Sumner's research is proved of great value.
A marine chemist issues gas free certificates and is certified by which organization?A.Mine Safety Appliance AssociationB.American Chemical SocietyC.Marine Chemists AssociationD.National Fire Protection Association
Which agency issues a certificate of loading that is evidence that the rules and regulations concerning bulk grain cargoes have been observed ________．A.American Bureau of ShippingB.Department of AgricultureC.National Cargo BureauD.Public Health Service
American government forbade Huawei and ZTE to invest in USA，because it thought( ) A.they made clumsy forays，and enemies B.they came for oil，agricultural land and other resources C.many deals were politicized and some were corrupt D.they might hurt American national security
American schools are divided into（）A、public schools and private onesB、Public schools,private schools and community schoolsC、coeducation schools and single sex schools.D、national schools and state-run schools
关于A/THR断开，下列说法错误的是（）A、如果通过按压FCU上A/THR衔接电门来断开A/THR，那么发动机的推力将立即转换至推力手柄当前位置所对应推力值B、通过按压推力手柄上A/THR断开按钮来断开A/THR，如果这时双发推力手柄都在档位中（in de tent），那么发动机将工作在A/THR断开前的推力C、如果通过按压FCU上A/THR衔接电门来断开A/THR，那么发动机的推力将保持在A/THR断开前的推力值D、通过按压推力手柄上A/THR断开按钮来断开A/THR，如果这时双发推力手柄都不在档位中（not in detent），那么发动机的推力将平稳的转换至推力手柄当前位置所对应的推力值
美国国家标准局（American National Standards Institute）ANSI是由公司、政府和其他组织成员组成的自愿组织，主要定义了（）的标准。A、802.3B、RFCC、FDDID、VPN
下列组成的两种细菌混在一起了：thr﹣leu﹣arg﹣met﹢和thr﹢leu﹢arg﹢met﹣，经过一定时间，将混合体置于基本培养基上，在基本培养基上生长出来的重组菌落的基因型是（）A、thr﹢leu﹣arg﹢met﹣B、thr﹣leu﹣arg﹣met﹢C、thr﹣leu﹢arg﹢met﹣D、thr﹢leu﹢arg﹢met﹢
关于A/THR，下列说法错误的是（）A、A/THR的功能包括推力保持和速度保持B、A/THR可以自动衔接也可以人工衔接C、A/THR可以自动断开也可以人工断开D、A/THR衔接后，只有两个推力手柄都在CLMB位，A/THR才能激活
用于起降的遥控器中THR、ELE通道分别控制多旋翼无人机的什么运动？（）A、THR（上升、下降）ELE（前后、俯仰）B、THR（前后、俯仰）ELE（上升、下降）C、THR（上升、前后）ELE（下降、俯仰）
当A/THR衔接且起作用时（）A、推力手柄控制ENG且FCU上的A/THR接通灯亮；B、推力手柄控制ENG但FCU上的A/THR接通灯不亮；C、推力系统控制ENG但FCU上的A/THR接通灯不亮；D、推力系统控制ENG且FCU上的A/THR接通灯亮。
若按下A/THR断开按钮并保持超过15秒钟，其结果是（）A、在余下的飞行中A/THR保持断开B、包括迎角保护在内的所有A/THR功能都丢失C、只能在下次FMGC通电时被重新恢复D、A+B+C
单选题The stars in the American national flag stand _____ the original thirteen colonies.AforBinCofDon
单选题在一个转导试验中，供体的基因型为leu+thr+azir，受体的基因型为leu-thr-azis。如选择leu+，就会发现azir的共转导频率50％，而thr+的共转导频率为2％，说明（）。A基因leu与azi比leu与thr更为接近B基因azi与thr比azi与lue更为接近Cleu与thr比leu与azi更为接近D都不正确
单选题Which of the followings is not an indication of a bad maintenance?（）Aa pipe with welded connectionsBa pipe with several clipsCa cement boxDa leaking valve
单选题In ship operations，hoisting and lowering pipe in and out of the drilled hole is the main function of the（）.AswivelBcathead spoolCdrawworksDstand pipe
单选题Hoses used for cargo transfer operations must be tested abdinspected at specified intervals by （）.Aa representative of the Captain of the PortBthe operator of the vessel or facilityCa representative of the National Cargo BureauDa representative of the American Bureau of Shipping