给定字符串中出现次数最多的单词

def find_most_frequent_word(string):
    words = string.split()
    word_count = {}
    for word in words:
        if word in word_count:
            word_count[word] += 1
        else:
            word_count[word] = 1
    most_frequent_word = max(word_count, key=word_count.get)
    return most_frequent_word

# 示例用法
string = "This is a test string. This string is a test."
most_frequent_word = find_most_frequent_word(string)
print("出现次数最多的单词是:", most_frequent_word)