方法一：

sentence = "I can because i think i can"
result = {word: sentence.split().count(word) for word in set(sentence.split())}
print(result)

方法二：

def count(str):
    count_words = str.split()
    count_word = {}
    for word in count_words:
        if word not in count_word.keys():
            count_word[word] = 1
        else:
            count_word[word] += 1
    return count_word

print(count('I can because i think i can'))

方法三：

from collections import Counter

str = 'I can because i think i can'
counts = Counter(str.split())
print(counts)