求给定自然数 m 和 n 的最大公约数。请完善程序。 Private Sub Command1_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r Do r = m Mod n m = n n = r Loop Until__________ Text3.Text = m End Sub Private Sub Command2_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r r = m Mod n Do Until _______ m = n n = r r = m Mod n Loop Text3.Text =____ End Sub Private Sub Command3_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r Do r = m Mod n m = n n = r Loop While________ Text3.Text =______ End Sub Private Sub Command4_Click() Dim m As Integer, n As Integer, r As Integer m = Text1.Text n = Text2.Text If m < n Then r = m: m = n: n = r r = m Mod n Do While______ m = n n = r r = m Mod n Loop Text3.Text =____ End Sub