【单选题】_______ difficult the task may be, we must finish it on time, because we can’t meet such a precious opportunity _______ we have expected.
【单选题】设A是3×4矩阵,B是3×5矩阵,如果AC T B有意义,则C是( )矩阵.
【单选题】We are quite sure that we can ________ our present difficulties and finish the task according to schedule.
【简答题】设 A 是 m × 3 矩阵 , B 是 n × 4 矩阵 , C 是 4 × s 矩阵 , 而已知 ABC 是 5 × 7 矩阵 , 则 m = ( ), n = ( ), s = ( ).
【简答题】设A是3×4矩阵,B是5×2矩阵,且乘积ACB有意义,则矩阵C T 的阶数为______。