8. There are 6 different elements of class A and 4 different elements of class B. An experiment requires an even number of elements from class A and at least 2 elements from class B. How many experimental schemes are there?

保留了原文的换行和格式。
8. Let $a_{r}$ and $b_{r}$ represent the number of ways to choose different elements from Class A and Class B, respectively. According to the problem, $a_{0}=1, a_{2}=C_{b}^{2}=15$, $a_{4}=C_{6}^{4}=15, a_{6}=1, a_{1}=a_{3}=a_{5}=0$, and the generating function for $\left\{a_{r}\right\}$ is $A(t)=1+15 t^{2}+15 t^{4}+t^{6}$; similarly, the generating function for $\left\{b_{r}\right\}$ is $B(t)=6 t^{2}+4 t^{3}+t^{4}$. Let $G(t)=A(t) B(t)=\left(1+15 t^{2}+15 t^{4}+t^{6}\right)\left(6 t^{2}+4 t^{3}+t^{4}\right)=$ $1+6 t^{2}+4 t^{3}+91 t^{4}+60 t^{5}+105 t^{6}+60 t^{7}+21 t^{8}+4 t^{9}+t^{10}$, which means the total number of experimental schemes is $1+6+4+91+$ $60+105+60+21+4+1=353$