泥浆河北安平中学高二英语（普通部）暑假作业（7月18日，无答案）

2021年1月14日发(作者：骆简)

河北安平中学高二英语暑假作业1
2019年07月18日 命题人：敬稳 审核人：门红颖
一、阅读理解 （每题2分，共22分）
[来源:]
[来源:学。科。网Z。X。X。K][来源:学。科。网]

1阅读短文,回答问题。
Many traffic jams leave drivers puzzled as they finally reach the end of a tailback to find no
visible cause for their delay. Now, a team of mathematicians have found the answer by developing
a model to show how major delays occur on our roads, with no obvious cause.
The model showed that a driver, slowing down below a critical speed (临界速率)when reacting
to unexpected events, forces the car behind to slow down further and the next car back to reduce
its speed still further. The result of this is that several miles back, cars would finally come to a stop,
with drivers unaware of the reason for their delay. The model predicts that this is a very typical
situation on a busy highway (above 15 vehicles per min). The jam moves backwards through the
traffic creating a so-called traveling wavedrivers may encounter many miles
upstream, several minutes after it was caused.
Drivers and policy-makers have not previously known why jams like this occur, though many
have put it down to the sheer volume of traffic. While this clearly plays a part in this new theory,
the main issue is around the smoothness of traffic flow. According to the model, heavy traffic will
not automatically lead to jams but can be smooth-flowing. This model takes into account the time
delay in drivers' reactions, which leads to drivers' braking more heavily than would have been
necessary if they had identified and reacted to a problem ahead a second earlier.
When a driver taps the brake, the traffic may come to a full standstill several miles behind. It
really matters how hard a driver brakes—a slight braking from a driver who has identified a
problem early will allow the traffic flow to remain smooth. Heavier braking, usually caused by a
driver reacting late to a problem, can affect traffic flow for many miles.
the passage,we leam that .
new theory lacks evidence and is not convinced
g at low speed leads to traffic jams
drivers don’t know how to deal with unexpected events
s are often unaware of the reason why a traffic jam happens
of the following is NOT included in the new theory?
traffic speed.
width of roads.
volume of traffic.
reaction time.A. mathematicians develop a model B. drivers react to problems earlyC. there
is a “backward traveling wave” D. there is a visible cause of the delay
c jams can be avoided when .
aticians develop a model
s react to problems early
is a “backward traveling wave”
is a visible cause of the delay
underlined word “this” in the third paragraph refers to .
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