题目：

解题过程：

模式A：

num = int(input("（模式A）输入数字："))               
for i in range(num):                         for j in range(num):                     if j < i + 1:                        print(j + 1, end=" ")            else:                                print("", end=" ")               print()                                  

模式B：

num = int(input("（模式B）输入数字："))              
for i in range(num):                        for j in range(num):                    if j < (num - i):                   if j != (num - i - 1):          print(j + 1, end=" ")       else:                           print(j + 1, end=" ")       else:                               print(" ", end=" ")             print()                                 

模式C：

num = int(input("（模式C）输入数字："))      
for i in range(1, num + 1):         for _ in range(num - i):        print(" ", end=" ")         for j in range(i, 0, -1):       print(j, end=" ")           print()                         

模式D：

num = int(input("（模式D）输入数字："))            
for i in range(num):                      for j in range(num):                  if j >= i:                        print(j - i + 1, end=" ")     else:                             print(" ", end=" ")           print()