写一个python程序，将数字转换成英文句子。具体规则如下: 1.在英语读法中三位数字看成一整体，后面再加一个计数单位。从最右边往左数，三位一单位，例如12,345 等 2.每三位数后记得带上计数单位 分别是thousand, million, billion. 3.公式：百万以下千以上的数 X thousand X, 10亿以下百万以上的数：X million X thousand X, 10 亿以上的数：X billion X million X thousand X. 每个X分别代表三位数或两位数或一位数。 4.在英式英语中百位数和十位数之间要加and，美式英语中则会省略，我们这个题目采用加上and，百分位为零的话，这道题目我们省略and 下面再看几个数字例句： 22: twenty two 100: one hundred 145: one hundred and forty five 1,234: one thousand two hundred and thirty four 8,088: eight thousand (and) eighty eight (注:这个and可加可不加，这个题目我们选择不加) 486,669: four hundred and eighty six thousand six hundred and sixty nine 1,652,510: one million six hundred and fifty two thousand five hundred and ten 说明： 数字为正整数，不考虑小数，转化结果为英文小写； 保证输入的数据合法 关键字提示：and，billion，million，thousand，hundred。

好的，您可以尝试这个Python程序来实现数字转换成英文句子的功能：

def num2eng(num):
if num == 0:
return "zero"
# 定义常量
units = ["", "thousand", "million", "billion"]
digits = ["", "one", "two", "three", "four", "five",
"six", "seven", "eight", "nine"]
tens = ["", "", "twenty", "thirty", "forty", "fifty",
"sixty", "seventy", "eighty", "ninety"]
teens = ["ten", "eleven", "twelve", "thirteen", "fourteen",
"fifteen", "sixteen", "seventeen", "eighteen", "nineteen"]
# 递归函数，将三位数及以下的数字转换成英文句子
def helper(num):
if num == 0:
return ""
elif num < 10:
return digits[num]
elif num < 20:
return teens[num - 10]
elif num < 100:
return tens[num // 10] + (" " + helper(num % 10) if num % 10 != 0 else "")
else:
return digits[num // 100] + " hundred" + (" and " + helper(num % 100) if num % 100 != 0 else "")
# 将数字分段并转换成英文句子
res = ""
for i in range(len(units)):
if num % 1000 != 0:
res = helper(num % 1000) + " " + units[i] + " " + res
num //= 1000
# 去除英文句子中的多余空格，并返回结果
return res.strip()

# 测试程序，输出一些样例结果
print(num2eng(22)) # twenty two
print(num2eng(100)) # one hundred
print(num2eng(145)) # one hundred and forty five
print(num2eng(1234)) # one thousand two hundred and thirty four
print(num2eng(8088)) # eight thousand eighty eight
print(num2eng(486669)) # four hundred and eighty six thousand six hundred and sixty nine
print(num2eng(1652510)) # one million six hundred and fifty two thousand five hundred and ten