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【简答题】
功的正负:功只有大小,没有方向,是标量,但功有正负之分。0≤θ<π/2时,物体_____;当 π/2<θ≤π时,物体______。当θ=π/2时,物体______。一个物体做负功,也可以说物体____这个力做了功。
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举一反三
【简答题】田间排水系统按空间位置可分为（）和竖井排水二大类。
【简答题】In Ireland, following the collection of a 15 euro cent per bag tax, plastic bag usage has dropped by ______.
【简答题】Ireland has a lot to offer the traveler besides its famously green countryside and popular traditional music. It is rich on【M1】______ prehistoric and Medieval ruins, fine Georgian architecture, and ar...
【单选题】Ireland has the following demographic features EXCEPT ______.
A.
a late marriage age
B.
an excess of females in the population
C.
a high proportion of bachelors and spinsters of all ages
D.
a low birthrate compounded by a century of emigration
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