题目

Moses Mendelssohn, the grandfather of the well-known German composer(作曲家), was far from being handsome. Along with a rather short stature(身材), he had a hunchback(驼背) . One day he visited a merchant in Hamburg who had a lovely daughter named Frumtje. Moses fell hopelessly in love with her. But Moses was refused by his ugly appearance When it was time for him to leave, Moses picked up his courage and climbed the stairs to her room to take one last chance to speak with her. She was a heavenly beauty, but caused him deep sadness by her refusal to look at him. After several attempts 20．函数y=ax2+bx+c（a≠0）的函数值均为正数，那么（　　）A．a＞0，△＜0B．a＜0，△≤0C．a＞0，△≥0D．a＞0，△＞0