文档内容
选择性必修第二册 Unit 4 Breaking boundaries
Ⅰ.阅读理解
A
Network-based technologies have become increasingly widespread，and they are now being
used by countless individuals ， professionals ， and businesses worldwide.Despite their
advantages，most network-based systems are highly at risk of malicious(恶意的) attacks.
The consequences of a malicious attack on network-based systems can be extremely
harmful.For instance，an attack on a power plant network could leave millions of individuals and
offices without electricity，while attacks on social media networks can lead to exposure of user
information.
To overcome the weaknesses of network-based systems，computer scientists worldwide have
been trying to develop advanced intrusion detection systems (IDSs) (入侵检测系统) that could
help to identify malicious attacks，increasing a network’s safety.In recent years，machine
learning (ML) algorithms(机器学习算法) have been found to be particularly promising for
automatically detecting attacks and intrusions on a network’s functioning.
An important step in the development and training of ML-based IDSs is the selection of data
features that a model can rely or focus on when making predictions.Ideally，by analyzing large
datasets，researchers should be able to identify the most suitable features for solving a given task
using ML tools，and this can also be applied to intrusion detection.
Researchers at Canadian University Dubai in the UAE have recently developed a new feature
selection method that could enable the development of more effective ML-based IDSs.This method
was found to perform remarkably well when compared with other commonly employed feature
selection techniques.Using the features they identified as most important for intrusion detection，
the researchers created a highly efficient ML-based detection system.This system was found to be
capable of distinguishing between DDoS attacks and harmless network signals with 99% accuracy.
In the future，the feature selection method developed by the researchers and their findings
could help the development of new，highly effective IDSs.In addition，the system they created
using the features they identified could be applied in real-world settings to detect malicious attacks
on real networks.
1．What does paragraph 1 focus on about network-based technologies?
A．Their targeted users. B．Their popularity.
C．Their potential risk. D．Their advantages.
2．How can IDSs increase the safety of networks?
A．By tracking malicious attacks. B．By starting anti-virus programs.C．By sorting out user information. D．By recognizing malicious attacks.
3．What is the key to the development of ML-based IDSs?
A．Solving given tasks.
B．Selecting reliable data features.
C．Making accurate predictions.
D．Analyzing large enough datasets.
4．What’s the purpose of the text?
A．To introduce a new technique for IDSs.
B．To promote network-based technologies.
C．To raise people’s awareness of network safety.
D．To discuss ways to deal with malicious attacks.
B
Beavers(海狸)，like humans，change their surroundings to fit their needs.Known as
nature’s engineers，they tear trees down to build homes to live in and dams to raise water levels
for protection from enemies.Dams also slow water’s flow while blocking sediment(沉积物) that
would otherwise flow downstream.The resulting wetlands often attract wildlife diversity where
none had existed.There are challenges，though.Beaver dams sometimes cause flooding，and most
people prefer trees alive and upright.
Communities face a delicate balancing act，learning to coexist with beavers.Last winter，
many people enjoying Winston Path became beaver fans as one furry family transformed Swallow
Pond into an oasis for birds，frogs，turtles and deer.
Yet such activity caused concern.As beavers worked，they raised water levels about five
feet.The increased depth allows beavers to survive underwater if the pond ices over.But county
officials were concerned about how higher water would affect the soil bank supporting Winston
Path.
To find a good balance between protecting the path and the beavers，the county introduced
a“beaver baffle”—a pond leveler.Beavers often rush to fill holes in their dams.Baffles stabilize
water levels by creating a hidden exit for high water to escape through the dam，unnoticed by the
beavers.
People love the beavers but they also love the mature trees.Recently，Catherine Jones,18，
organized a tree-caging event—putting wire cloth around large tree trunks to discourage beavers
from biting them.It also protects people from injury due to random trees falling.“We cover the
trees we don’t want them to eat ， while planting periodically others they like ， ” said
Jones.“We need to learn to give up a little of our wants to share the Earth’s resources.”
Swallow Pond’s 2023 project will restore proper water depth and improve wildlife habitat
without creating problems for the path.The balancing act continues.
5．What is the first paragraph mainly about?A．Where beavers’ favorite surroundings are.
B．What effects beavers have on their habitat.
C．Why beavers are called nature’s engineers.
D．How beavers help attract wildlife diversity.
6．Why did the beaver family’s activity cause concern?
A．Swallow Pond would flood often.
B．Sediment would flow downstream.
C．The popular path might be damaged.
D．Beavers might have to live underwater.
7．What do the underlined words “beaver baffle” refer to in paragraph 4?
A．A block to keep beavers away.
B．A tool to fix holes in the dams.
C．A device to maintain water level.
D．A material to protect the soil bank.
8．What is the theme of Swallow Pond’s 2023 project?
A．Biological diversity. B．Harmonious coexistence.
C．Prevention of natural disasters. D．Preservation of wildlife habitat.
Ⅱ.完形填空
On the night of the speech contest，I was worried about the shy girl.My heart 1 when I
knew the boy on stage previous to her， 2 ，was fairly successful with his humor and personal
style.The whole audience burst out a wave of 3 almost every 30 seconds.
My palms(手掌) began to 4 .It was the first time that she had been on the stage，so I
couldn’t blame her for any 5 .The strong spotlight made her so insignificant that nobody 6
she had been on the stage.
But the moment that 7 me occurred.I clearly heard a 8 voice，“Now，your 9
，please！” The whole audience fell quiet.Small and thin as the girl appeared，the 10 look
on her face instantly caught everyone’s eyes.Then her speech was on ，logical and well-
organized.Words of power 11 freely out of the girl like magic.When her speech 12 ，a
thunderous applause sounded from the audience.When the competition was concluding，all of us
waited 13 for the winner’s name to be called.Tears of joy 14 my vision when the host
announced she won first prize.Holding the medal tightly，she gave me a brilliant smile.I 15
her into my arms，too excited to say any words.
1．A.beat B．sank C．lost D．broke
2．A.sure enough B．worse still C．above all D．in addition
3．A.crying B．warning C．clapping D．screaming
4．A.sweat B．tremble C．change D．turn5．A.try B．pose C．guess D．slip
6．A.thought B．admitted C．ignored D．noticed
7．A.confused B．interested C．surprised D．challenged
8．A.loud B．weak C．tight D．low
9．A.support B．attention C．vote D．silence
10．A.determined B．puzzled C．relaxed D．bored
11．A.crowded B．hurried C．bounced D．flowed
12．A.started B．ended C．progressed D．rested
13．A.sincerely B．easily C．wildly D．eagerly
14．A.misted B．hid C．prevented D．shaded
15．A.pushed B．threw C．pulled D．lifted
Ⅲ.语法填空(★)
In 2020 ， the Nobel Peace Prize 1. (award) to the World Food
Programme(WFP) for its efforts to fight hunger，for its contributions to improving conditions for
peace in conflict-affected areas，and for its efforts to prevent the use of hunger as a weapon of war
and conflict.
The WFP,2. (found) in 1961，is the largest food-assistance branch of the United
Nations.In emergencies，it is often the first on the scene，delivering food assistance to the victims
of wars，civil conflicts，earthquakes，and crop 3. (fail) due to natural disasters.In
2019，the UN organization helped 97 million people in 88 countries 4. were victims
of serious food insecurity and hunger，the 5. (high) number since 2012.
In 2015，ending hunger was adopted 6. one of the UN’s Sustainable
Development Goals.Primarily ， the WFP works to realize this goal.It works hard 7.
(help) people who cannot produce or obtain enough food for 8. (they) and their
families.
The WFP plays 9. important role in fighting hunger for world peace.The
Nobel Committee wishes to emphasize that providing aid to increase food security not just 10.
(effective) prevents hunger，but also helps to promote stability and peace.
