3. Given the ellipse $C: \frac{x^{2}}{8}+\frac{y^{2}}{4}=1$, for any real number $k$, the length of the chord intercepted by the ellipse $C$ from the following lines cannot be equal to the length of the chord intercepted by the line $l$ : $y=k x+1$ is
A. $k x+y+k=0$
B. $k x-y-1=0$
C. $k x+y-k=0$
D. $k x+y-2=0$
Solve
\[
\left\{
\begin{array}{l}
y=k x+1, \\
x^{2}+2 y^{2}=8
\end{array}
\Rightarrow\left(2 k^{2}+1\right) x^{2}+4 k x-6=0
\right.
\]
\[
\Rightarrow|A B|=\sqrt{k^{2}+1} \cdot \frac{\sqrt{16 k^{2}+24\left(2 k^{2}+1\right)}}{2 k^{2}+1}=\sqrt{k^{2}+1} \cdot \frac{\sqrt{64 k^{2}+24}}{2 k^{2}+1} \text {, }
\]

Solve
\[
\left\{
\begin{array}{l}
-y=k x-2, \\
x^{2}+2 y^{2}=8
\end{array}
\Rightarrow\left(2 k^{2}+1\right) x^{2}-8 k x=0
\right.
\]
\[
\Rightarrow|C D|=\sqrt{k^{2}+1} \cdot \frac{\sqrt{64 k^{2}}}{2 k^{2}+1} \neq \sqrt{k^{2}+1} \cdot \frac{\sqrt{64 k^{2}+24}}{2 k^{2}+1} \text {, so choose } D.
\]