题目

At the bad news，she was so sad ______ I had to stay here keeping her ______. A．that；companion      B．then；companies C．that；company    D．and；accompany 答案：C如果a、b是方程x2-3x+1=0的两根，那么代数式a2+2b2-3b的值为（ ）A.6 B.－6 C.7 D.－7