Help with no_numerals code challenge (Python)

Question

So i finished my first code challenge today and am very happy about it.
The challenge was to write a code that swaps out numbers from 0 to 10 for their respective number words, e.g 0 for zero.
Even tho i could solve it I'm not quite happy with it, since I'm sure there are smarter ways to check for a 10 in a sentence, maybe with some smart re?

Your ideas are very much appreciated :) Code below

import re

num_dic = {
'1': 'one', '2': 'two', '3': 'three', '4': 'four',
'5': 'five', '6': 'six', '7': 'seven', '8': 'eight',
'9': 'nine', '0': 'zero', '10': 'ten',
}

pattern = r"^[0-9]

Answer 1

a=input("")
d={"1":"one","2":'two',"3":'three',"4":'four',"5":'five',"6":'six',"7":'seven',"8":'eight',"9":'nine',"10":'ten',"0":'zero'}
x=a.split(' ')
for i in x:
if i in d.keys():
u=x.index(i)
x[u]=d[i]
o=" ".join(x)
print(o)