LyX：如何在常规文本模式下更改希腊字母的字体样式？

Question

在 LyX 的常规文本模式下，我需要使用一些希腊字母。
我通过“插入”-“特殊字符”-“符号”-“希腊语”插入希腊字母。
我得到的结果是

但我想要得到的是

我的序言是

%{{ Don't change! times font for proper scaling
\usepackage{mathptmx}
\usepackage[scaled=.90]{helvet}
\usepackage{courier}
%}} times font for proper scaling

\usepackage[numbers,square]{natbib} %see http://merkel.zoneo.net/Latex/natbib.php for usage!
\usepackage{url}
\usepackage{xtab, tabularx} %for multipage tables
\usepackage[Sonny]{fncychap} %for the chapter headings
\usepackage{makeidx}
\usepackage{float}

%{{ set double-space
\usepackage{setspace}
\doublespacing
%}} set double-space

%set margins
\usepackage[top=1in, bottom=1in, left=1.25in, right=1.25in]{geometry}

% Define your own commands and environment definitions, for example:
\newcommand{\prograenter code herem}[1]{\textbf{#1}} % program names in bold text
\newcommand{\exten}[1]{\texttt{#1}} % file extensions in bold text (use caps)
\newcommand{\cmmd}[1]{\textbackslash\texttt{#1}} % command name in tt font
\newcommand{\enviro}[1]{\texttt{#1}} % environment name in tt font

\newenvironment{definition}[1]{\begin{quote}\emph{#1}:}{\end{quote}}
  % Provides indented formal definition and emphasizes the word.
  % e.g. \begin{definition}{Reliability} ... \end{definition} % Put the document title and page numbers in the header

\pagestyle{headings}
\pagenumbering{roman}

%Place floats within section
\usepackage[section]{placeins}

% To be able to capitalize cross reference
\usepackage{cleveref}