网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
单选题
One of the main functions of wearing rings, as used in a centrifugal pump, is to （）.
A
maintain radial alignment between the pump impeller and casing
B
absorb all impeller shaft end thrust
C
prevent water leakage to the atmosphere
D
prevent wear of the pump casing and/or impeller
参考答案
参考解析
解析：
暂无解析
更多 “单选题One of the main functions of wearing rings, as used in a centrifugal pump, is to （）.A maintain radial alignment between the pump impeller and casingB absorb all impeller shaft end thrustC prevent water leakage to the atmosphereD prevent wear of the pump casing and/or impeller” 相关考题
考题
He had some statues in his study. One was a lady ______ nothing but a bath towel.A: woreB: wearsC: to wearD: wearing
考题
Luckily I was wearing a seat belt. If I hadn’t been wearing one, I____seriously.A.would be injuredB.will have been injuredC.will be injuredD.would have been injured
考题
Among the rings of a piston the ______one is subjected to the greatest load and temperature.A.bottomB.middleC.topD.any position
考题
A fire pump may be used for other purposes if ______.A.the other services are run off a reducing station with a pressure gageB.one of the required pumps is kept available for use on the fire main system at all timesC.no relief valves are installedD.all of the above conditions are met
考题
What is the function of wearing rings found on some centrifugal pumps ________．A.Absorb erosion of high velocity discharge streamB.Seal pump shaft against entry of airC.Isolate the outlet side from the inlet sideD.Dampen the turbulent discharge flow
考题
which one of the following should maria do to display the release date in a text column?（）A、used the number and time format options B、used the @date to text functions to convert time to text C、concatenated the date types using mathematical operators D、used the @text functions to convert time and number data to text in text columns
考题
Which two statemets are true？（）A、DPT/RPR uses a bi-directional ring consisting of two symmetric counter rotating fibre rings.B、DPT/RPR is defined in the IEEE 802.17 standard and it uses Token Bucket system to avoid collisions on the fiber.C、In DPT/RPR rings， data packets can be sent in one direction （downstream） and the corresponding control packets in the opposite direction （upstream），thus using both fibres concurrently to maximise bandwidth.D、DPT/RPR can be deployed in the Core of the SP networks where point-to-point POS links are used tomake best use of the Bandwidth.
考题
Which two statements about subqueries are true? （）A、A subquery should retrieve only one row.B、A subquery can retrieve zero or more rows.C、A subquery can be used only in SQL query statements.D、Subqueries CANNOT be nested by more than two levels.E、A subquery CANNOT be used in an SQL query statement that uses group functions.F、When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.
考题
You are designing a site topology for the new Active Directory environment. What should you do?（）A、Create one site for all offices. Place the subnets for the four branch offices and the Sydney main office in this site. B、Create two sites: one site for the four branch offices and one site for the Sydney main office. Place the subnets for the branch offices in one site. Place the subnet for the Sydney main office in the other site. C、Create three sites: one site for the four branch offices, one site for the Sydney main office, and one site for the Sydney satellite offices. D、Create four sites: one for the Melbourne and Perth branch offices, one site for the Berlin and Paris branch offices, one site for the Sydney main office, and one site for the Sydney satellite offices. E、Create five sites; one site for the Melbourne branch office, one site for the Perth branch office, one site for the Berlin branch office, one site for the Paris branch office, and one site for the Sydney main office. Place the subnets for each branch office and the Sydney main office in their respective sites.
考题
单选题What is a function of the wearing rings used in most centrifugal pumps?（）A
Absorb erosion of high velocity discharge streamB
Seal pump shaft against entry of airC
Isolate the discharge side from the suction sideD
Dampen the turbulent discharge flow
考题
单选题In order to keep excess oil from the intake ports in two-stroke/cycle diesel engines, （）A
wide compression rings are usedB
oil rings are located above the pistonC
chromium plating is used on all piston ringsD
oil rings are located near the bottom of the piston skirt
考题
单选题Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）A
starting the engine while hotB
knurling the piston skirtC
operating the engine overheatedD
scuff resistant piston rings
考题
单选题If you were operating a centrifugal water service pump with worn wearing rings, the （）.A
pump would be very noisyB
pump would vibrate excessivelyC
pump would develop insufficient flowD
stuffing box would leak excessively
考题
单选题Multiple fire pumps may be used for other purposes provided that one pump is（）.A
on line to the fire mainB
kept available for use on the fire main at all timesC
capable of being connected to the fire mainD
rated at or above 125 psi
考题
单选题The purpose of the wearing rings used in a centrifugal pump is to （）.A
prevent an internal explosion in the pump when it is overheatedB
enable a visual inspection of the pump while it is runningC
insure a proper alignment of the pump coupling to the driverD
accommodate for friction between the impeller and the easing
考题
多选题Which two are true about aggregate functions?（）AYou can use aggregate functions in any clause of a SELECT statement.BYou can use aggregate functions only in the column list of the select clause and in the WHERE clause of a SELECT statement.CYou can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.DYou can pass column names, expressions, constants, or functions as parameter to an aggregate function.EYou can use aggregate functions on a table, only by grouping the whole table as one single group.FYou cannot group the rows of a table by more than one column while using aggregate functions.
考题
单选题Which features of a centrifugal pump reduce the need for renewing worn impellers and pump casings?（）A
Close radial clearance between impeller hub and casingB
Low rotational speed of impellerC
Removable end plateD
Replaceable impeller and casing wearing rings
考题
多选题Which two statements about subqueries are true? （）AA subquery should retrieve only one row.BA subquery can retrieve zero or more rows.CA subquery can be used only in SQL query statements.DSubqueries CANNOT be nested by more than two levels.EA subquery CANNOT be used in an SQL query statement that uses group functions.FWhen a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.
考题
单选题If an operating bilge pump is developing good vacuum, but is unable to discharge any water, which of the following problems is the most probable cause?（）A
The wearing rings are excessively wornB
The suction strainer is cloggedC
The discharge valve is cloggedD
The shaft is worn
考题
单选题What is true of using group functions on columns that contain NULL values?（）A
Group functions on columns ignore NULL values.B
Group functions on columns returning dates include NULL values.C
Group functions on columns returning numbers include NULL values.D
Group functions on columns cannot be accurately used on columns that contain NULL values.E
Group functions on columns include NULL values in calculations if you use the keyword INC_NULLS.
考题
单选题Fuel oil transfer systems used onboard diesel propelled vessels are required to have （）.A
two fuel oil transfer pumps provided where one is to be independent of the main engineB
two fuel oil transfer pumps, with a combined capacity exceeding the maximum consumption of the main engineC
engine driven transfer pumps and only used in constant speed applicationsD
the capacity of the engine driven pump exceed the consumption rate of the engine to which it is attached
考题
单选题For IKE phase 1 negotiations， when is aggressive mode typically used？（）A
when one of the tunnel peers has a dynamic IP addressB
when one of the tunnel peers wants to force main mode to be usedC
when fragmentation of the IKE packet is required between the two peersD
when one of the tunnel peers wants to specify a different phase 1 proposal
考题
单选题Which of following functions is not one of the functions of air conditioner?（）A
refreshing the airB
making person upsetC
adjusting the air humidityD
adjusting the air temperature
热门标签
最新试卷
