题目

 It is said that bad living habits as well as dirty surroundings, stuffy room and some other factors _______ the wide spread flu. A. result from                                                        B. benefit from C. devote to                                                            D. contribute to将一元二次方程（1+3x）（x+3）=2x2+1化为一般形式是______，它的二次项系数是______；一次项系数是______；常数项是______．