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【简答题】
雷达发射或收到返回电磁波时均会在屏上出现一个锯齿波．当用雷达探测敌方飞行目标时，指示器的荧光屏上出现如图所示的两个锯齿波形．若电磁波在空气中传播速度为3×10 8 m/s，则敌方飞行目标离雷达站的距离为 _____ m．
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【单选题】—What are you going to do this afternoon? — I will probably play computer games ________ my parents are out.
A.
as far as
B.
as long as
C.
even if
D.
as if
【简答题】朝食暮吐，暮食朝吐者是因（ ）|吐势徐缓，吐物清稀者是因（ ）A. 胃热津伤B. 食滞胃脘C. 脾胃阳虚D. 饮停于胃E. 颅内肿瘤
【单选题】—My parents don't allow me _______ computer games at school. —That's right. They are bad for your study. [ ]
A.
play
B.
plays
C.
playing
D.
to play
【单选题】Seeing their son playing computer games all day, the parents don’t know ______ it.
A.
how to do
B.
what to do
C.
how to deal with
D.
how to do with
【单选题】Parents what games their children always play.
A.
worry on
B.
worry with
C.
worry about
D.
worry from
【单选题】What is ranked by parents as the greatest threat to boys?
A.
Gang crimes.
B.
Online games.
C.
Extreme sports.
D.
Dangerous traffics.
【单选题】Is it that you often play computer games ________ worries your parents?
A.
why
B.
that
C.
which
D.
what
【单选题】To the parents' worry, some middle school students are ______ computer games and completely forget their studies. [ ]
A.
crazy about
B.
very fond of
C.
concerned for
D.
serious about
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