Only 4 out of the 6 test cases are correct, what am I doing wrong? . It's the No Numeral exercise

Question

sentence = str(input()).lower()
phrase = sentence.split(" ")
numbers = {"10":"ten", '0':'zero', '1':'one', '2':"two", '3':'three', '4':'four', '5':'five', "6":"six", "7" : 'seven', '8':'eight', '9':'nine'}
output = ""
for item in phrase:
output+=numbers.get(item, item) + " "
print(output)

Answer 1

It's not necessary to change all characters to lowercase.

sentence = input()