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举一反三
【单选题】加速器的等中心是指（）
A.
机架的旋转中心与束流中心一致
B.
机架的旋转中心与小机头旋转中心一致
C.
机架的旋转中心与治疗床的旋转中心相一致
D.
机架的旋转中心、束流中心与治疗床旋转中心一致
E.
机架的旋转中心、小机头旋转中心、治疗床旋转中心与束流中心相一致
【单选题】Passage One Gravity is a slippery beast. We don’t know how strong it is, how it works or how fast its effects move. But this year we made progress. October saw the most accurate measurem...
A.
Newton and Einstein had similar opinions on the speed of gravity
B.
the author of the passage is in favor of Einstein’s thought about the speed of gravity
C.
astronomers think that both Newton and Einstein were wrong on the speed of gravity
D.
Newton’s thought about the gravitational effect is out of date
【单选题】Gravity is a slippery beast. We don’t know how strong it is, how it works or how fast its effects move. But this year we made progress. October saw the most accurate measurement yet of Newton’s gravit...
A.
two things far apart might vibrate in unison
B.
the ripples in space-time are only imagined
C.
there exist gravitational waves
D.
abrupt, violent cosmic events lead to gravitational waves