已知集合A={x|ax²﹣5x+6=0}，若A中元素至少有一个，则a的取值范围是____．

阅读理解

    William Henry Harrison, the ninth President of the USA, was born in a small town. When he was a boy, he was very quiet and shy. Because he was so quiet, everyone thought that he wasn't bright. People in the town often put a nickel(五分镍币)and a dime(十分硬币)before him and asked him which to choose. He always chose the nickel and they laughed.

    One day a woman felt sorry for him. She asked, "Why do you never take a dime and always choose a nickel? Do you know a nickel is worth(值……钱) much less than a dime?"

    "Certainly I know it.” William answered slowly. "But if I choose the dime, they will not ask me to choose them any more.”

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①两岸直航表明两岸不再敌对，以和解取代冲突
②“三通”可增加台湾优势、重振台湾竞争力
③符合两岸同胞利益，符合两岸关系发展需要，符合历史前进潮流
④实现“三通”后，两岸关系将迎来一个大交流、大合作、大融合、大发展的崭新局面

下列词语中不含贬义的一项是(　　)。

已知二次函数y=ax²（a≠0）与一次函数y=kx﹣2的图象相交于A、B两点，如图所示，其中A（﹣1，﹣1），