你能帮帮他们吗
一列由A向B方向传播的横波,波速为24m/s.A与B相距为3m,从某时刻开始观察A、B两点的振动图象如图,则该波的频率应
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一个正数和一个负数相加,结果要取决于它们的绝对值,异号两数相加,绝对值相等时和为?(即相反数之和为?)
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1/X(X+2)+1/(X+1)(X+3)+1\(X+2)(X+4)+.+1/(X+2007)(X+2009)
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while he was looking for me i saw him first同义句___he was look
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Jenny is ___,so she always does well in her schoolwork.那个空填f
1年前