我将提供一个英文句子以及与它相关的上下文, 请你帮我检查句子中是否有单词拼写错误、语法错误以及标点符号错误, 如果有, 请指出错误并按照如下JSON格式进行修正后返回结果, 如果没有, 请返回actions为空list:
{
    "source_sentence": "原句子",
    "fixed_sentence": "修正后的句子",
    "actions": [
        {
            "error_label": "在原句中进行的错误位置标注",
            "fixed_result": "当次action执行之后的结果",
            "src": "错误标注位置的内容",
            "dst": "修正后的内容",
            "action": "replace/delete/insert_before/insert_after",
            "error_type": "拼写错误/语法错误/标点错误",
            "explanation": "对错误的解释以及修改的说明"
        },
        ...
    ]
}

#注意:
1. 一共支持四种类型的action
- replace: 替换 src 位置的内容为 dst
- delete: 删除 src 位置的内容
- insert_before: 在 src 位置之前插入 dst, 这里 dst 仅为被插入的内容, 不包括 src 本身
- insert_after: 在 src 位置之后插入 dst, 这里 dst 仅为被插入的内容, 不包括 src 本身
2. actions 中的每个元素仅执行一次标注和一次动作修改, 其中 error_label 是当次标注的位置, fixed_result 是当次修改后的结果(而非最终修改的结果)
3. 每次动作都是基于前一次动作执行的结果进行处理, 即每次动作的 error_label 都是在前一次动作的 fixed_result 的基础上进行标注的
4. 如果句子中存在错误, 则error_labal中一定要出现错误标注, 且 src 中的内容一定和 error_label 中使用 ** 标注的内容一致
5. 你可以依据context来进行全文的基础时态判断
6. 你需要纠正的是语法/词汇拼写/标点符号错误, 不要随意修改用户的用词问题

<example>
input_sentence: I like read a books a.
output: {
    "source_sentence": "I likes read a boks. too.",
    "fixed_sentence": "I like to read books, too.",
    "actions": [
        {
            "error_label": "I **likes** read a boks. too.",
            "fixed_result": "I like read a boks. too.",
            "src": "likes",
            "dst": "like",
            "action": "replace",
            "error_type": "语法错误",
            "explanation": "因为 "I" 是单数主语，动词 "like" 应该用单数形式。"
        },
        {
            "error_label": "I like read a **boks**. too.",
            "fixed_result": "I like read a books. too.",
            "src": "boks",
            "dst": "books",
            "action": "replace",
            "error_type": "拼写错误",
            "explanation": "单词"book"的复数正确写法为"books"。"
        },
        {
            "error_label": "I like read **a** books. too.",
            "fixed_result": "I like read books. too.",
            "src": "a",
            "dst": "",
            "action": "delete",
            "error_type": "语法错误",
            "explanation": "爱好读书的常见表达方式是"read books", 因为爱好读书肯定不是一本书, 因此不能用 a 修饰 books。"
        },
        {
                "error_label": "I like **read** books. too.",
                "fixed_result": "I like to read books. too.",
                "src": "read",
                "dst": "to",
                "action": "insert_before",
                "error_type": "语法错误",
                "explanation": "表达喜欢做某事应该用 like to do sth. 或 like doing sth. 但like 后面不可以直接跟动词。"
        },
        {
            "error_label": "I like to read books**.** too.",
            "fixed_result": "I like to read books, too.",
            "src": ".",
            "dst": ",",
            "action": "replace",
            "error_type": "标点错误",
            "explanation": "一般使用逗号来连接too和其前面的句子。"
        }
    ]
}
</example>

下面给出你要处理的句子和其上下文, 你暂时不需要给出JSON输出, 首先请你针对输入内容详细思考你的操作步骤, 请使用中文输出
<input_sentence>
When I stepped there, I sank under ice.
</input_sentence>
<input_context>
When I was eleven years old, I had a big accident. I get scared even now when I think about that time. I went skating near my house. There were many people, and I saw some of them falling on the ice.
It was my first time to go ice skating, so I was nervous. I was wondering how to skate.
I went with a friend who was very skillful. He spent some time teaching me how to skate, but I didn't learn much. He left me and skated all around. As soon as he left, I fell down. I envied the other people because they could skate well.
I was bored because I kept falling so I took off my skates and just walked around on the ice in my shoes. It was cold and my hands were frozen.
Suddenly, I stepped on something that was not hard. What was it? It was a weak place in the ice. When I stepped there, I sank under ice. I thought that I was going to die, but I did my best to grab something to get out from under the ice. I tried to grab the edge of the ice, but it was very difficult for an eleven-year' old child.
It seemed like a very long time, like a year. Then, fortunately, someone helped me. He grabbed my arms and pulled me up. So, I lived and I'm still alive today.
I thanked him. At that time, my friend came back. I was annoyed at him because he was supposed to take care of me, but he didn't. He was embarrassed. When I took a taxi home, the taxi driver was surprised and asked what had happened. I didn't want to say anything because I was tired and scared. Even now, whenever I think about that time, I feel uncomfortable. I don't want to go skating again even now.
</input_context>