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设 A 是 m×n 矩阵,存在 nxm 矩阵 C 和 D,使 Tc4=1,和 AD=1m.证明 m=n和C=D.
1年前
My sister met him at the Grand Theatre yesterday aftemoon , so he _____ your lecture. [ ]
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When I was young, I was always frustrated ( 挫败的 )
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若sin(30-x)=1/3,则cos(120+2x)等于?
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Don't put your things ________(到处). Put them away, please.
1年前