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 pum

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单选题

One of the main functions of wearing rings, as used in a centrifugal pump, is to （）.

maintain radial alignment between the pump impeller and casing

absorb all impeller shaft end thrust

prevent water leakage to the atmosphere

prevent wear of the pump casing and/or impeller

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相似问题和答案

第1题：

Among the rings of a piston the ______one is subjected to the greatest load and temperature.

A.bottom

B.middle

C.top

D.any position

正确答案：C

第2题：

What is the function of wearing rings found on some centrifugal pumps ________．

A.Absorb erosion of high velocity discharge stream

B.Seal pump shaft against entry of air

C.Isolate the outlet side from the inlet side

D.Dampen the turbulent discharge flow

正确答案：C

第3题：

He had some statues in his study. One was a lady ______ nothing but a bath towel.

A: wore

B: wears

C: to wear

D: wearing

参考答案：D

第4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.
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正确答案:A,C

第5题：

Mostly used MPI functions，MPI最常用的函数：（）。

正确答案:MPI_Wait， MPI_Allreduce， and MPI_Bcast

第6题：

A fire pump may be used for other purposes if ______.

A.the other services are run off a reducing station with a pressure gage

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C.no relief valves are installed

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正确答案：B

第7题：

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正确答案:D

第8题：

Luckily I was wearing a seat belt. If I hadn’t been wearing one, I____seriously.

A.would be injured

B.will have been injured

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参考答案：D

第9题：

What are the main functions of Parliament?

正确答案:The main functions of Parliament are:
(1) to pass laws;
(2) to provide the means of carrying on the work of government by voting for taxation;
(3) to examine government policy and administration, including proposals for expenditure;
(4) to debate the major issues of the day.

第10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.
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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.

正确答案:B,F

One of the main functions of wearing rings, as used in a cen

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