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【简答题】
根据本学期所学内容,谈谈学习心得体会,字数1000字以上。
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皮皮学刷刷变学霸
举一反三
【单选题】A person pulls a box along the ground at a constant speed. If we consider Earth and the box as our system, what can we say about the net external force on the system?
A.
It is zero because the system is isolated.
B.
It is nonzero because the system is not isolated.
C.
It is zero even though the system is not isolated.
D.
It is nonzero even though the system is isolated.
E.
none of the above
【简答题】利用左图所示图片,制作出如右图所示的木板雕花效果。
【简答题】Consider a dynamic system
【简答题】利用左图所示图片,制作出如右图所示的扇子效果。