82 The size relationship of the numbers $a=\frac{10^{1988}+1}{10^{1989}+1}, b=\frac{10^{1987}+1}{10^{1988}+1}, c=\frac{10^{1987}+9}{10^{1988}+9}$ is
A. $a>b>c$
B. $a<b<c$
C. $a<c<b$
D. $c<a<b$
82 B.
$$
\begin{array}{l}
a=\frac{10^{1988}+1}{10^{1989}+1}<\frac{10^{1988}+10}{10^{1989}+10}=\frac{10^{1987}+1}{10^{1988}+1}=b, \\
b=\frac{10^{1987}+1}{10^{1988}+1}<\frac{10^{1987}+9}{10^{1988}+9}=c,
\end{array}
$$

Therefore, $a<b<c$.