19． At a conference on self﹣driving cars，Mike Harp，a government official，asked a
seemingly simple question about what happens when his own car meets a driverless vehicle."If
I honk（按喇叭） ，will it do any good？"Harp wanted to know.Unfortunately，manufacturers
didn't have an answer."We haven't reached that point of deciding how and whether it would be
appropriate for vehicles to react and in which way to honking，"said one of them.The brief
exchange highlights a thorn in the side of automakers and policymakers alike：Self﹣driving
cars will have to share the road with human drivers，likely for decades to come.Those vehicles
must therefore respond and adapt to the peculiarities and mistakes of humans behind the wheel.
Self﹣driving technology has already come a long way.Cars being tested on the road today
use cameras and radar，for example，to detect the movements of nearby cyclists and
pedestrians.There are already driver﹣assist technologies built into some cars that monitor the
speed of vehicles around you，detect potential accidents before they occur，and automatically slow
or stop the car to avoid a wreck.In a world where all cars drive themselves，the technology could
operate at peak efficiency.Supporters of self﹣driving cars say that speed limits could be raised
and fatal crashes largely avoided as no traffic laws are broken and poor drivers become a thing of
the past.
But the change to driverless vehicles is expected to be gradual，and will likely start with ride
﹣sharing services，as the costs of personally owning a self﹣driving car remain extremely
high.That means man and machine will have to play nice on roadways."There are so many
interesting situations，"such as honking a horn，Harp said.When"another car with a driver meets a
self﹣driving car without a driver in there and they realize that，it will frighten some people.How
that's going to be dealt with will be part of the fun part of this process."
Any driver can tell you that driving involves a lot of social interaction，particularly the hand
gestures and eye contact of fellow drivers.Much of that interaction between drivers will eventually
be digital as cars increasingly collect data and share it with the vehicles around them.If a car
speeds up，slows down or prepares for a stop，for example，that would be communicated
immediately and electronically to the other vehicles on the road.Like self﹣driving technology，
however，it will be years before the vehicle﹣to﹣vehicle communication is common.
That challenge is being taken into account as driverless vehicles are tested on public
roads.But the honking issue is particularly tricky because it's subject to interpretation.It's going to
be really hard for a driverless vehicle，even if it hears the honk，to figure out what that honk means.
（1）In paragraph 1，"a thorn"refers to C .
A.the issue that human drivers have peculiarities and make mistakes
B.the prediction that self﹣driving cars will be common in the future
C.the fact that driverless cars co﹣exist with cars driven by humans
D.the technology that ensures driverless cars are safe on the road
（2）Which of the following can be inferred from the last two paragraphs？ D
A.Most people don't advocate self﹣driving technology.
B.Inter﹣vehicle communication is superior to inter﹣personal interaction.
C.Social interaction will decrease among drivers behind the wheel.
D.More data is needed to make self﹣driving technology a reality much sooner.
（3）Which example is used to illustrate that self﹣driving technology is not something new？
D
A.A car communicates its speed to the other vehicles.
B.A driverless car is likely to frighten human drivers.
C.Speed limits are raised in a world of self﹣driving cars.
D.Car cameras and radar are used to detect moving people.
（4）Which of the following might be the best title of the passage？ D
CDDD