要点在于，end=""表示下个print不换行
实例：
1 for x in range (1,10): 2 for y in range(1,10): 3 if x>=y: 4 print(x,"x",y,"=",x*y," ",end="") 5 print()
输出结果
1 x 1 = 1 2 x 1 = 2 2 x 2 = 4 3 x 1 = 3 3 x 2 = 6 3 x 3 = 9 4 x 1 = 4 4 x 2 = 8 4 x 3 = 12 4 x 4 = 16 5 x 1 = 5 5 x 2 = 10 5 x 3 = 15 5 x 4 = 20 5 x 5 = 25 6 x 1 = 6 6 x 2 = 12 6 x 3 = 18 6 x 4 = 24 6 x 5 = 30 6 x 6 = 36 7 x 1 = 7 7 x 2 = 14 7 x 3 = 21 7 x 4 = 28 7 x 5 = 35 7 x 6 = 42 7 x 7 = 49 8 x 1 = 8 8 x 2 = 16 8 x 3 = 24 8 x 4 = 32 8 x 5 = 40 8 x 6 = 48 8 x 7 = 56 8 x 8 = 64 9 x 1 = 9 9 x 2 = 18 9 x 3 = 27 9 x 4 = 36 9 x 5 = 45 9 x 6 = 54 9 x 7 = 63 9 x 8 = 72 9 x 9 = 81
