1. If $x=2^{n+1}+2^{n}, y=2^{n-1}+2^{n-2}$, where $n$ is an integer, then the quantitative relationship between $x$ and $y$ is ( ).
(A) $x=4 y$
(B) $y=4 x$
(C) $x=12 y$
(D) $y=12 x$
$\begin{array}{l}\text {-1.A. } \\ x=2^{n+1}+2^{n}=2^{2}\left(2^{n-1}+2^{n-2}\right)=4 y .\end{array}$

The translation is as follows:

$\begin{array}{l}\text {-1.A. } \\ x=2^{n+1}+2^{n}=2^{2}\left(2^{n-1}+2^{n-2}\right)=4 y .\end{array}$

Note: The original text is already in a mathematical form that is the same in both Chinese and English, so the translation is identical to the original.