Sub Main()
    Dim i As Long
    For i = 11 To 251
        If Not IsEmpty(Range("M" & i)) Then _
            Range("B" & i) = Range("M" & i)
        If Not IsEmpty(Range("N" & i)) Then _
            Range("C" & i) = Range("N" & i)
    Next i
End Sub

此代码只将非空值从M和N列复制到B和C

下面这段代码应该可以做到这一点：

Sub CopyRangeToRange()
    Dim CpyFrom As Range
    Dim Cell As Range

    Set CpyFrom = ActiveSheet.Range("M11:N251")

    For Each Cell In CpyFrom
        If Cell.Value <> vbNullString Then
            Cell.Offset(0, -11).Value = Cell.Value
        End If
    Next Cell
End Sub