我怎样才能将以下短语“从何时起，按照已经为单项式建立的规则”左对齐（水平）？

Question

我希望我的短语more向左侧移动。

    \documentclass[11pt,a4paper]{article}
    \usepackage{blindtext}
    \usepackage{mathtools}
    \usepackage{IEEEtrantools}
\begin{document}
\begin{IEEEeqnarray*}{rCl}
(3a+2b)^{2}&=&\{(3a)+(2b)\}^{3}\\
&=&(3a)^{3}+3(3a)^{2}(2b)+3(3a)(2b)^{2}+(2b)^{3},\\
\rlap{whence, by rules already established for monomials,}\\
&=&27a^{3}+54a^{2}b+36ab^{2}+8b^{3}.
\end{IEEEeqnarray*}
\end{document}

Answer 1

   \documentclass[11pt,a4paper]{article}
    \usepackage{blindtext}
    \usepackage{mathtools}
    \usepackage{IEEEtrantools}
\begin{document}
\begin{IEEEeqnarray*}{rCl}
(3a+2b)^{2}&=&\{(3a)+(2b)\}^{3}\\
&=&(3a)^{3}+3(3a)^{2}(2b)+3(3a)(2b)^{2}+(2b)^{3},\\
\shortintertext{whence, by rules already established for monomials,}
&=&27a^{3}+54a^{2}b+36ab^{2}+8b^{3}.
\end{IEEEeqnarray*}
\end{document}