1. Given that $a_{1}, a_{2}, \cdots, a_{2002}$ are all positive numbers, and satisfy
$$
\begin{array}{l}
M=\left(a_{1}+a_{2}+\cdots+a_{2001}\right)\left(a_{2}+a_{3}+\cdots+a_{2001}\right), \\
N=\left(a_{1}+a_{2}+\cdots+a_{2002}\right)\left(a_{2}+a_{3}+\cdots+a_{2001}\right) .
\end{array}
$$

Then the relationship between $M$ and $N$ is ( ).
(A) $M>N$
(B) $M=N$
(C) $M<N$
(D) Cannot be determined
$-1 .(\mathrm{A})$.
Let $T=a_{2}+a_{3}+\cdots+a_{2001}$. Then we have
$$
\begin{aligned}
M & =\left(a_{1}+T\right)\left(T+a_{2002}\right) \\
& =T^{2}+a_{1} T+a_{2002} T+a_{1} a_{2002}, \\
N & =\left(a_{1}+T+a_{2002}\right) T=T^{2}+a_{1} T+a_{2002} T . \\
\because & M-N=a_{1} a_{2002}>0, \therefore M>N .
\end{aligned}
$$