Message in Chinese (Simplified) (中文(简体))
        无法为只读字段“<var>X</var>”的成员传递 ref 或 out (在构造函数中除外)
Unlocalized message
        Members of readonly field '<var>X</var>' cannot be passed ref or out (except in a constructor)
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无法为只读字段“<var>X</var>”的成员传递 ref 或 out (在构造函数中除外)

Members of readonly field '<var>X</var>' cannot be passed ref or out (except in a constructor)
Search by Google