无法使用Python在CSV文件中插入完整字符串

import csv

def insert_string_to_csv(csv_file, row_index, column_index, string):
    # 读取CSV文件
    with open(csv_file, 'r', encoding='utf-8') as file:
        reader = csv.reader(file)
        rows = list(reader)

    # 在指定位置插入完整字符串
    rows[row_index][column_index] = '"' + string + '"'

    # 写入CSV文件
    with open(csv_file, 'w', encoding='utf-8', newline='') as file:
        writer = csv.writer(file)
        writer.writerows(rows)

# 示例用法
csv_file = 'data.csv'
row_index = 2
column_index = 3
string = '完整字符串'

insert_string_to_csv(csv_file, row_index, column_index, string)