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【简答题】
Both sides have been ________________ their positions after yesterday's fierce fighting. (reinforce)
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举一反三
【单选题】One of the few things you _____ say about English people with certainty is that they talk a lot about the weather. [ ]
A.
can
B.
must
C.
should
D.
need
【单选题】It is implied in the passage that one of the reasons that people often talk about UFOs may be that ______.
A.
they want to tell lies
B.
they don't live in the large cities
C.
there are only few witnesses
D.
the cases are interesting although not reliable
【单选题】One of the few things you ______say about English people with certainty is that they talk a lot about the weather. [ ]
A.
need
B.
must
C.
can
D.
should
【简答题】把正方形ABCD沿其对角线AC折成直二面角D-AC-B后，连接BD，得到如图所示的几何体，已知点O、E、F分别为线段AC、AD、BC的中点。 （1）求证：AB∥平面EOF； （2）求二面角E-OF-B的大小。
【简答题】在如图所示的几何体中，四边形ABCD为正方形， 为直角三角形， ，且 . （1）证明：平面 平面 ； （2）若AB=2AE，求异面直线BE与AC所成角的余弦值.
【单选题】如图所示,长方体ABCD-A1B1C1D1中,底面A1B1C1D1是边长为1的正方形,高CC1= ,则直线AC1与底面ABCD所成的角的大小是( )
A.
30°
B.
45°
C.
60°
D.
90°
【简答题】把正方形ABCD沿其对角线AC折成直二面角D-AC-B后，连接BD，得到如图所示的几何体，已知点D、E、F分别为线段AC、AD、BC的中点， (1)求证：AB∥平面EOF； (2)求二面角E-OF-B的大小．
【单选题】The author states that one important reason that we do not talk much about poverty is that ______.
A.
no one knows what to do about it
B.
poverty really is lower than in the past
C.
no one has been left out of the current boom
D.
the president is not concerned about the poor
【简答题】如图所示，在正方体ABCD-A 1 B 1 C 1 D 1 中，AB=a，E为棱A 1 D 1 中点． （I）求二面角E-AC-B的正切值； （II）求直线A 1 C 1 到平面EAC的距离．
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