python - TypeError:格式字符串的参数不足-使用While循环

我正在做旧的99瓶歌曲，并试图做它使用一个While循环，以帮助我继续更好地学习循环类型。
我想知道为什么在下面的代码中会出现TypeError，我到底缺少了哪些参数？
这是我的代码：

# Get number of beers
bottles = int(raw_input("How many bottles of beer? "))

# return invalid response
if bottles < 1:
    print "That's not a good number"

    if bottles == 1:
        s1 = "bottle"
        s2 = "bottles"

    elif bottles == 2:
        s1 = "bottles"
        s2 = "bottles"

# sing verses
while bottles > 0:
    print "%d %s of beer on the wall," % bottles, s1
    print "%d %s of beer." % bottles, s1
    print "You take one down, pass it around,"
    print "%d %s of beer on the wall." % (bottles - 1), s2
    print
    bottles -= 1

下面是错误：

Traceback (most recent call last):
    File "beer.py", line 47, in <module>
          print "%d %s of beer on the wall," % bottles, s1
TypeError: not enough arguments for format string

我试过在%后面的“瓶子，s1”周围加上括号，但还是没有用。有什么建议吗？

最佳答案

必须将多个参数指定为元组，例如

print "%d %s of beer on the wall," % (bottles, s1)