设函数f（x）=x²+ax+b，a，b∈R．

（1）若a+b=3，当x∈1，2时，f（x）≥0恒成立，求实数a的取值范围；

（2）是否存在实数对（a，b），使得不等式|f（x）|＞2在区间1，5上无解，若存在，试求出所有满足条件的实数对（a，b）；若不存在，请说明理由．

阅读下面短文，根据短文内容回答问题。

    My name is Grace. Today is Sunday. It is a nice day. It is also my grandfather's birthday. He is 80 years old. My parents and I go to his home. We don't get up early because the alarm clock (闹钟) doesn't work. We don't have much time for breakfast. We go to a supermarket to buy some fruit and a birthday cake at eight thirty. Then we go to my grandparents' home quickly. We get there at 11:15. My grandparents are very happy to see us. We have lunch at 12 o'clock. After lunch, we play chess with my grandfather. It is interesting. We go home at about four o'clock in the afternoon. It is a happy day.

用显微镜观察植物细胞装片的同一部位，若想在视眼中看到的细胞数目最多，应该选择的组合是（　　）

下列句中加线的成语使用不恰当的一项是（     ）

研究经济问题通常需要通过调查搜集量化数据，并加以统计分析。某学生研究小组了解到，
烟草行业尽管上缴可观的税收和利润，却也让社会付出了极大代价。于是他们准备以此为主题，研究社会为烟草消费所付出的经济成本。以下选项中可以作为调查统计项目的是 ( )
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