Why it keep saying I miss some words from the string?

# E.g. word_count("I am that I am") gets back a dictionary like:
# {'i': 2, 'am': 2, 'that': 1}
# Lowercase the string to make it easier.
# Using .split() on the sentence will give you a list of words.
# In a for loop of that list, you'll have a word that you can
# check for inclusion in the dict (with "if word in dict"-style syntax).
# Or add it to the dict with something like word_dict[word] = 1.

def word_count(words):
    dict = {}
    test = words[:]
    for key in words:
        count = 0
        while True:

            try:
                test.remove(key)
                count += 1
                dict.update({key:count})
            except:
                break

    return dict