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We can't ________ making a plan. Cleanup Day is only two weeks from now.
1年前
有的人独自学习效率高,有的人与其他同学一起学习效果好;有的人晚上学习效率高,而有的人早晨学习状态最好。这说明 [ ]
1年前
She said that ______ (加入) the English club was the best way to improve your English.
1年前
People are using more and more natural gas, wind and other forms of _____. [ ]
1年前
已知二次型f(x1,x2,x3,x4)通过正交变换化为标准型y1^2+2y2^2-3y3^2,则该二次型的符号差是多少,求详解.
1年前