题目
黑洞是一种密度极大的天体，以至包括光在内的所有物质都逃脱不了其引力的作用。2019年4月10日，人类发布了首张黑洞照片，如图所示。该黑洞位于室女座一个巨椭圆星系M87的中心，据观测有一距此黑洞中心r的星体，以周期T绕其做匀速圆周运动。光在真空中传播速度为c。由此可推断，此黑洞的半径至多为（ ）A. B. C. D.Have you felt annoyed when a cellphone rings during
the class? Something must be done to stop this．Now in
New York City, USA，a rule is carried out in schools．Students can’t even bring cellphones to schoo1．Is it a good thing or not?
Anxious parents say that cellphones are an important
tool in holding New York city’s families together．
“I worry about it，” said
Elizabeth Lorris Ritter, a mother of a middle school kid．
It’s necessary in our everyday life．We have a washing machine. We have running water, and
We have cellphones．”
Many American parents think cellphones connect them to
their children on buses，getting out from subways, walking through
unknown places．
“I have her call me when she gets out of school，”said Lindsay Walt, a schoolgirl’s mother． “No one in New York is going to let their child go to
school without a cellphone”
What about the cellphone owners, the students? Most of
the students said cellphones were essential and the cellphone was like
all extra(额外的)hand or foot for them．
“I feel so empty，”said May
Chom，1 4．There is also
no way to listen to music on the way to school without my phone．It will be a really, really boring trip．”
1.You can use a cellphone___________．
A．to enjoy
listening to music
B．to work as
running water
C．to work as a
washing machine
D．to send
children to school
2.Which of the following statements is TRUE?
A． Many
American parents don’t think cellphones are necessary for the
students．
B．Cellphones
only bring troubles to the school life．
C． Cellphones
connect children with their families when they are outside．
D． All the
school children agreed not to use cellphones at school.
3.What does the underlined word “essential” mean in
Chinese?
A．时髦的． B．必要的． C．昂贵的． D．浪费的
4.The article is about the____ in carrying out the
rule not to use a cellphone in schoo1．
A．happiness B．interest C．problem D．satisfaction
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