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【单选题】
一单能X射线通过3个半价层的厚度后强度为原来的A.
1／2
B.
1／3
C.
1／4
D.
1／8
E.
1／16
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参考解析：
知识点：
皮皮学刷刷变学霸
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【简答题】设sin ＝ ，则sin 2 θ ＝ ．
【简答题】已知sin（π﹣α）=﹣2sin（ +α），则sinα·cosα=( )
【单选题】Delimbing gate works as ______.
A.
Single-stem delimbing with transverse feeding
B.
Multi-stem delimbing with lengthwise feeding
C.
Multi-stem delimbing with transverse feeding
【简答题】已知 sinθ+cosθ sinθ-cosθ =2 ，则sin2θ=______．
【单选题】在谈及俄罗斯出兵乌克兰时,美国《芝加哥论坛报》认为:“这是美国与欧洲的慕尼黑时刻。”下列对发生在“一个世纪以前的‘慕尼黑时刻’”评述不正确的是
A.
英、法推行的“绥靖政策”达到顶峰
B.
加速了第二次世界大战的爆发
C.
确保了欧洲的安全
D.
企图将祸水引向苏联
【简答题】若 sinθ+cosθ sinθ-cosθ =2，则sin（θ-5π）?sin ( 3π 2 -θ) =______．
【单选题】Stem Cell Therapy May Help Repair the Heart According to scientists in the USA, stem cell therapy may one day be able to repair the hearts of people with heart failure. Researchers at Pittsburgh Unive...
A.
Right
B.
Wrong
C.
Not mentioned
【单选题】Why do some people oppose stem cell research according to the man?
A.
They don't know about the benefits of the research.
B.
The research goes against their religious beliefs.
C.
The research costs too much money.
D.
They insist that the research is against nature.
【简答题】已知tan（π+α）=2，则 sinα+sin( π 2 +α) sinα+cos(π-α) =______．
【简答题】已知sin（π-α）=-2sin（ π 2 +α），则sinα?cosα=______．
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