1. Let the sets be
$$
\begin{array}{l}
M=\{u \mid u=12 m+8 n+4 l, m, n, l \in \mathbf{Z}\}, \\
N=\{u \mid u=20 p+16 q+12 r, p, q, r \in \mathbf{Z}\} .
\end{array}
$$

Then the relationship between $M$ and $N$ is ( ).
(A) $M=N$
(B) $M \subset N$
(C) $N \subset M$
(D) $M \not \subset N, N \not \subset M$
$-1 . A$.
Let $m=n=0$, then $12 m+8 n+4 l=4 l$. Therefore, $M$ is the set of all multiples of 4.
Let $p=0, q=3 k+l, r=-4 k-l$, then $20 p+16 q+12 r=4 l$.