单选题If a few injector spray holes become plugged, the result could be （）A excessive surging at governed speedB combustion knock under loadC poor fuel combustionD all of the above

题目

单选题

If a few injector spray holes become plugged, the result could be （）

excessive surging at governed speed

combustion knock under load

poor fuel combustion

all of the above

参考答案和解析

正确答案： A

解析：暂无解析

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相似问题和答案

第1题：

第一组

Older loop scavenged engines may have a single injector mounted centrally in the cylinder head. Because the exhaust valve is in the center of the cylinder head on modern uniflow scavenged engines the fuel valves (2 or 3) are arranged around the periphery of the head. The pressure at which the injector operates can be adjusted by adjusting the loading on the spring. The pressures at which the injectors operate vary depending on the engine, but can be as high as 540 bar. Some injectors have internal cooling passages in them extending into the nozzle through which cooling water is circulated. This is to prevent overheating and burning of the nozzle tip. Injectors on modern engines do not have internal cooling passages. They are cooled by a combination of the intensive bore cooling in the cylinder head being close to the valve pockets and by the fuel which is re-circulated through the injector when the follower is on the base of the cam or when the engine is stopped. As well as cooling the injector, re-circulating the fuel when the engine is stopped keeps the fuel at the correct viscosity for injection by preventing it from cooling down. Fuel injectors must be kept in good condition to maintain optimum efficiency, and to prevent conditions arising which could lead to damage within the cylinder. Injectors should be changed in line with manufacturers&39; recommendations, overhauled and tested. Springs can weaken with repeated operation leading to the injector opening at a lower pressure than designed. The needle valve and seat can wear which together with worn nozzle holes will lead to incorrect atomization and dribbling.

Modern uniflow scavenged engines have______.

A.a single injector mounted in the center of the cylinder head

B.several injectors mounted around the external boundary of the cylinder head

C.a single injector mounted at the external boundary of the cylinder head

D.several injectors mounted in the center of the cylinder head

正确答案：B

第2题：

An increase in the fuel injection pump discharge pressure can be caused by a/an _______.

A.leaking delivery valve

B.excessive bearing end play

C.plugged injector spray hole

D.increased plunger stroke

正确答案：C

第3题：

(ii) Explain whether or not Carver Ltd will become a close investment-holding company as a result of

acquiring either the office building or the share portfolio and state the relevance of becoming such a

company. (2 marks)

正确答案：
(ii) Close investment holding company status
Carver Ltd will not become a close investment-holding company if it purchases the office building as, although it will no
longer be a trading company, it intends to rent out the building to a number of tenants none of whom is connected to
the company.
Carver Ltd will become a close investment holding company if it purchases a portfolio of quoted shares as it will no
longer be a trading company. As a result it will pay corporation tax at the full rate of 30% regardless of the level of its
profits.

第4题：

共用题干
B1i'k Holes

1 Black holes can be best described as a sort of vacuum,sucking up everything in space. Scientists
have discovered that black holes come from an explosion of huge stars. Stars that are near death can no longer
burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,
hydrogen ends up putting pressure onto the star' s surface until it suddenly explodes then collapses.
2 Black holes come from stars that are made of hydrogen,other gases and a few metals. When these
explode it can turn into a stellar-mass ( 恒星质量）black hole , which can only occur if the star is large enough
(should be bigger than the sun) for the explosion to break it into pieces,and the gravity starts to compact
every piece into the tiniest particle. Try to see and compare:if a star that' s ten times the size of the sun ends
up being a black hole that' s no longer than 70 kilometers ,then the Earth would become a black hole that' s
only"fraction of an inch!
3 Objects that get sucked in a black hie will always remain there,never to brsak fren. But remember
that black holes can only gobble up（吞噬）objects within a specific distance to it It' s possible for a large
star near the sun to become a black hole,but the sun will continue to stay in place. Orbits (轨道）do not
change because the newly formed black hole, contains exactly the same amount of mass as when it was a star,
only this time its mass is totally contracted that it can end up as on biggeer tnan a state.
4 So far, astronomers have figured out that black holes exist because of Albert Einstenin's theory of
relativity. In the end,through numerous studies ,they have discovered that black holes truly exist. Since black
holes trap light and do not give off light,it is nearly impossible to detect black goles via a telescope. But
astronomers continue to study galaxies (银河系）,space and the solar system to understand how black holes
misht evolve. It is possible that black holes can exist for millions of years,and later contribute to a bigger
process in galaxies ,which can eventually lead to creation of new entities（实体）.Scientists also credit black
holes as helpful in learning how galaxies began to form.

Albert Einstein's theory of relativity helps to prove____________.
A: the existence of black holes
B: the creation of new entities
C: the same amount of mass
D: an explosion of huge stars
E: a fraction of an inch
F: the tiniest narticle

答案：A

解析：

第一段描述了什么是黑洞，以及它产生的缘由―巨型恒星爆炸，并叙述了恒星爆炸的原因和简要过程。再看选项，只有F项符合题意。
第二段的主要内容是：恒星来自由氢气、其他气体和一些金属组成的恒星；当这些物质爆炸时，恒星就变成了质量与原先的恒星等同的黑洞，恒星的每个碎片都被重力压缩成极小的颗粒。观察选项，似乎E、F两项都可选，但一则上一小题只能选F项，二则此段虽也讲了黑洞是怎么形成的，但比较侧重黑洞形成过程中，原来的恒星变成极小的颗粒。由第三段最后一句也可知，这些颗粒的质量总和与原来的恒星一样，正是这些颗粒使黑洞有极大的吸附性，而成其为“黑洞”。因此，黑洞就是由这些极小却质量巨大、吸附性极强的颗粒构成的。故选E。
第三段描述了黑洞极大的吸附性，及其具有如此大的吸附性的原因。黑洞形成后，周围一定距离内的几乎一切东西都会被吞噬而难以逃脱，故选A。
第四段主要讲黑洞存在的依据及科学家们的研究和设想。故选B。
由第一段第二句“…black holes come from an explosion of huge stars.”可知答案。
由第二段第二句后半部分“…the gravity。tartst。。ompact evey piece into the tiniest particle”可知答案。
由第三段最后一句“…the newly formed black hol。Contains。xactly the same amount of mass as when it was a star…”可知答案。
由第四段第一句话可知答案。第4部分：阅读理解第一篇本文主要讲的是科学家利用植物的光合作用使其生产氢气等可供人类使用的能源。

第5题：

共用题干
Black Holes

Most scientists agree that black holes exist but are nearly impossible to locate.A black
hole in the universe is not a solid object,like a planet,but it is shaped like a sphere（球体）.
Astronomers（天文学家）think that at the center of a black hole there is a single point in
space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.
If the singularity theory is correct,it means that when a massive star collapses,all the
material in it disappears into the singularity.The center of a black hole would not really be a
hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by
its great gravity.
Although black holes do exist,they are difficult to observe.These are the reasons.
No light or anything else comes out of black holes.As a result,they are invisible to
a telescope.
In astronomical terms,black holes are truly tiny.For example,a black hole formed
by the collapse of a giant star would have an event horizon（视界）only 18 miles across.
The nearest black holes would be dozens of light years away from Earth.One light
year is about 6 trillion（万亿）miles. Even the most powerlul telescopes could not pick out
an object so small at such a great distance.
In 1994 the Hubble Space Telescope provided evidence that black holes exist.There
are still answers to be found,however,so black holes remain one of the mysteries of the
universe.

The nearest black holes are hundreds of light years away from us.
A:Right
B:Wrong
C:Not mentioned

答案：B

解析：

第6题：

Springs in fuel injectors will become not strong enough to work because______.

A.the injector opens at a lower pressure than designed

B.the needle valve and seat wear out

C.the nozzle holes wear out

D.long time in use

正确答案：D

第7题：

Paragraph 2_____________
A:What Happens to the Objects Around a Black Hole?
B:Is There Proof That Black Holes Really Exist?
C:How Were Black Holes Named?
D:What Are Different Types of Black Holes?
E:What Are Black Holes Made of?
F:How Are Black Holes Formed?

答案：E

解析：

第8题：

It was almost impossible for an Indian to get even a ___________ education and even more difficult, as a result, for an Indian to become somebody in society .

A、fair

B、bone

C、wake

D、anxious

正确答案：A

第9题：

Black holes are formed after_____________.
A: the existence of black holes
B: the creation of new entities
C: the same amount of mass
D: an explosion of huge stars
E: a fraction of an inch
F: the tiniest narticle

答案：D

解析：

第10题：

共用题干
Black Holes

1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists
have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer
burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,
hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.
2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these
explode it can turn into a stellar-mass（恒星质量) black hole , which can only occur if the star is large enough
(should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact
every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends
up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S
only a fraction of an inch!
3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember
that black holes can only gobble up（吞噬）objects within a specific distance to it.It's possible for a large
star near the sun to become a black hole,but the sun will continue to stay in place.Orbits（轨道）do not
change because the newly formed black hole contains exactly the same amount of mass as when it was a star,
only this time its mass is totally contracted that it can end up as no bigger than a state.
4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of
relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black
holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But
astronomers continue to study galaxies（银河系）, space and the solar system to understand how black holes
might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger
process in galaxies,which can eventually lead to creation of new entities（实体）.Scientists also credit black
holes as helpful in learning how galaxies began to form.

When a large star explodes,the gravity compacts every piece into______.
A:the existence of black holes
B:the creation of new entities
C:the same amount of mass
D:an fraction of an inch
E:a fraction of an inch
F:the tiniest particle

答案：F

解析：

第一段描述了什么是黑洞，以及它产生的缘由―巨型恒星爆炸，并叙述了恒星爆炸的原因和简要过程。再看选项，只有F项符合题意。
第二段的主要内容是：恒星来自由氢气、其他气体和一些金属组成的恒星；当这些物质爆炸时，恒星就变成了质量与原先的恒星等同的黑洞，恒星的每个碎片都被重力压缩成极小的颗粒。观察选项，似乎E、F两项都可选，但一则上一小题只能选F项，二则此段虽也讲了黑洞是怎么形成的，但比较侧重黑洞形成过程中，原来的恒星变成极小的颗粒。由第三段最后一句也可知，这些颗粒的质量总和与原来的恒星一样，正是这些颗粒使黑洞有极大的吸附性，而成其为“黑洞”。因此，黑洞就是由这些极小却质量巨大、吸附性极强的颗粒构成的。故选E。
第三段描述了黑洞极大的吸附性，及其具有如此大的吸附性的原因。黑洞形成后，周围一定距离内的几乎一切东西都会被吞噬而难以逃脱，故选A。
第四段主要讲黑洞存在的依据及科学家们的研究和设想。故选B。
由第一段第二句“...black holes come from an explosion of huge stars.”可知答案。
由第二段第二句后半部分“...the gravity starts to compact every piece into the tiniestparticle”可知答案。
由第三段最后一句“…the newly formed black hole contains exactly the same amount of mass as when it was a star...”可知答案。
由第四段第一句话可知答案。

If a few injector spray holes become plugged, the result cou

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