你好，目前我知道可以用"｛｝".format(x(格式化字符串变量，但在多行字符串(在这种情况下是一个长html页面字符串(中如何精确地做到这一点？因为如果我把这些"｛｝.format(("放在像这样的多行字符串中，它肯定会以字符串的形式返回。
因为这就是问题所在，我只需要为电子邮件正文生成html_string，但一些变量，如下载链接，必须在这里。更不用说一个特殊的场景，取决于是否有bool。
def generate_html_body(attachment_bool: bool,download_link: str):
if attachment_bool is False:
Letter_1 = "Helaas was deze te groot om via mail door te sturen."
Letter_2 = "Klik hier om het bestand te downloaden."
if attachment_bool is True:
Letter_1 = "U vindt het bestand terug in de bijlage."
Letter_2 = "Is het bestand niet in de bijlage terug te vinden? Klik dan hier en download dan hier."
html_string="""<html>
<head>
<title>{{ title }}</title>
</head>
<body>
<p>Uw GIPOD data is gereed,</p>
<p> { Letter_1}</p>
<a href="{}"> {{ Letter_2 }} </a>
<p> U heeft 30 dagen de tijd om deze te downloaden. Bedankt om CLASSIFIED te gebruiken. </p>
<table>
<tr>
<td>
<p>
<![if !vml]><img width=500 height=500 src="" alt="logo" class="img-responsive"><![endif]>
</p>
</td>
</tr>
<tr>
<td>
<p></p>
</td>
<td>
</td>
</tr>
<tr>
<td>
<p>
<span></span>
</p>
</td>
</tr>
<tr>
<td>
<p>
<span style='font-size:10.0pt;line-height:105%;font-family:Roboto;color:#00273F'>
classiefie<o:p></o:p>
</span>
</p>
</td>
</tr>
<tr>
<td>
<p>
<b>
<span>
<a href="classiefie"">
<span style='color:#0563C1'>classiefie"/span>
</a>
</span>
</b><span></span>
</p>
</td>
</tr>
<tr>
<td>
<p>
<span></span>
</p>
</td>
</tr>
<tr>
<td>
<p>
<b>
<span lang=NL style='font-size:7.0pt;line-height:105%;font-family:Roboto;
color:#5EBA00;'>
Gelieve rekening te houden met het milieu
voordat u dit document afdrukt<o:p></o:p>
</span>
</b>
</p>
</td>
</tr>
<tr>
<td>
<p>
<span></span>
</p>
</td>
</tr>
<tr>
<td>
<p>
<span>
<![if !vml]><img img width=500 height=500 src="classiefie">
</span>
</p>
</td>
</tr>
</table>
</body>
</html>"""
str.format()适用于多行字符串，我在Flask应用程序中将其用于HTML，没有任何问题。
print("""
Here's the number I want to show you: {number}
""".format(number=42)
)
输出：
Here's the number I want to show you: 42
我个人更喜欢使用f-string：
number = 42
print(f"""
Here's the number I want to show you: {number}
"""
)
输出：
Here's the number I want to show you: 42