您需要查看标题字段的定义：

You need to look at the definition of the header field:

http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.14.17

Content-Type =Content-Type：media-type

Content-Type = "Content-Type" ":" media-type

因此需要单个媒体类型，这是由你在上面引用的语法定义的。

so it takes a single media-type, which is defined by the grammar you quoted above.

所以答案是：单个类型/子类型，后跟可选参数。

So the answer is: a single type/subtype, followed by optional parameters.