How can a line skip a column in an aligned environment?

Question

I'm trying to align an equation block with eight terms in the following layout:

A....... B..............
C.....   D....    E......
F......  G......  H...

I've tried just leaving out the third column in the first line, but that pushes the third column far right:

\begin{gather}
\begin{aligned}
&\text{A.......} &&\text{B..............} \\
&\text{C.....}   &&\text{D....}    &&\text{E......} \\
&\text{F......}  &&\text{G......}  &&\text{H...}
\end{aligned}
\end{gather}

If this were a table, I would merge the second and third cells of the first row using \multicolumn.

How can I position E and H before the end of B?

Answer 1

Depending on the width of B..., you can set it inside a \mathrlap:

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{gather}
  \begin{aligned}
    &\text{A.......} && \mathrlap{\text{B..............}} \\
    &\text{C.....}   && \text{D....}    && \text{E......} \\
    &\text{F......}  && \text{G......}  && \text{H...}
  \end{aligned}
\end{gather}

\end{document}

Answer 2

Why not use aray? With it is siple (as you noted in question):

\documentclass{article}
\usepackage{amsmath}
\usepackage{makecell}

\begin{document}
    \begin{equation}
    \begin{equation}
    \setcellgapes{3pt}
    \makegapedcells\bigotimes
\begin{array}{lll}
\gamma^2 = \alpha^2 + \beta^2  
                &\multicolumn{2}{l}{\displaystyle
                \sin{x}= \sum_{i=0}^{\infty}\frac{(-1)^i}{(2i+1)!}x^{2i+1}
                                    }                       \\
\text{C.....}   &\text{D....}    &\text{E......}            \\
\text{F......}  &\text{G......}  &\text{H...}
\end{array}
    \end{equation}
\end{document}