Strikethrough, bold, italic, superscript and subscript

# Strikethrough, Bold, Italic, Superscript and Subscript

## Character Effects and Horizontal Lines

### Strikethrough
If you need to insert a strikethrough in a document, the tag block used is `<s>`, for example:
```
这是一个<s>删除线</s>
```

The above content will be rendered as follows:

这是一个<s>删除线</s>

### Italic
If you need to format part of a document as italic, you need to use `*` or `_`, with 1 on each side wrapping the content, as shown below:
```
这是一个*斜体*
这是一个_斜体_
```

The above content will be rendered as follows:
这是一个*斜体*

### Bold

If you need to format part of a document as bold, you need to use `*` or `_`, with 2 on each side wrapping the content, as shown below:
```
这是一个**粗体**
这是一个__粗体__
```

The above content will be rendered as follows:
这是一个**粗体**

### Bold Italic

If you need to format part of a document as bold italic, you need to use `*` or `_`, with 3 on each side wrapping the content, as shown below:
```
这是一个***粗斜体***
这是一个___粗斜体___
```

The above text will be rendered as follows:

这是一个***粗斜体***

### Superscript and Subscript

If you need to format part of a document as superscript or subscript, you need to use the `` or `` tags to wrap the content, as shown below:
```
上标：X2
下标：O2
```

The above text will be rendered as follows:

上标：X2
下标：O2

### Abbreviation

**Abbreviation (same as the HTML abbr tag)**

> That is, the abbreviated form of a longer word or phrase, provided that HTML tag recognition is enabled, which is enabled by default

The <abbr title="Hyper Text Markup Language">HTML</abbr> specification is maintained by the <abbr title="World Wide Web Consortium">W3C</abbr>.