Simplify by combining like terms. \[ -8 x^{2}-8 x y-6 y^{2}-2 x^{2}-x y+4 y^{2} \] \[ -8 x^{2}-8 x y-6 y^{2}-2 x^{2}-x y+4 y^{2}=\square \] (Simplify your answer. Do not factor.)

Step 1 ：The question is asking to simplify the given expression by combining like terms. Like terms are terms that have the same variables and powers. The like terms in the given expression are $-8x^2$ and $-2x^2$, $-8xy$ and $-xy$, and $-6y^2$ and $4y^2$. We can combine these like terms by adding or subtracting them.

Step 2 ：Combine $-8x^2$ and $-2x^2$ to get $-10x^2$.

Step 3 ：Combine $-8xy$ and $-xy$ to get $-9xy$.

Step 4 ：Combine $-6y^2$ and $4y^2$ to get $-2y^2$.

Step 5 ：So, the simplified expression is $-10x^2 - 9xy - 2y^2$.

Step 6 ：\(\boxed{-10 x^{2}-9 x y-2 y^{2}}\) is the final answer.