[题1.8]将下列函数展开成最小项表达式-|||-(1) _(1)=AB+BC+CA-|||-(2) _(2)=S+overline (RQ)-|||-(3) _(3)=overline (Q)+overline (KQ)-|||-(4) _(4)=overline (AB)+overline (B)C-|||-(5) _(5)=overline (A)overline (B)overline (CD)+overline (ABC)