将字符串str="monday tuesday wednesday thursday friday saturday sunday"打印，将里面的小写day替换为大写，输入是否替换，每次替换只能替换一个？替换完成打印字符串！用python写

你可以使用Python的字符串操作和循环来实现这个功能。首先，创建一个函数，然后逐个处理每个单词并将小写的“day”替换为大写。以下是具体的代码示例：

def replace_days():
    str_input = "monday tuesday wednesday thursday friday saturday sunday"
    
    days_to_replace = ["tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"]
    replaced_str = ""
    
    for word in str_input.split(" "):
        if word.lower() == "day":
            print(f"是否替换 '{word}' (y/n)?")
            user_choice = input().lower()
            
            if user_choice == "y":
                while True:
                    replacement = input("请输入新的大写字母：")
                    if replacement.isupper():
                        replaced_str += replacement + " "
                        break
                    else:
                        print("请输入一个大写字母！")
            else:
                replaced_str += word + " "
                
        else:
            replaced_str += word + " "
    
    print("替换后的字符串:")
    print(replaced_str)

replace_days()

运行上述代码后，它会提示你是否替换每个“day”，如果你选择替换，程序会等待你输入一个大写字母。如果你选择不替换，原样保留。替换完成后，会打印出修改后的字符串。