设，点集的点满足下列所有条件：①；②；③；④；⑤。则的边界是一个有几条边的多边形     （   ）

某学生欲观测果蝇控制某种酶合成的基因X对于细菌A的反应，因此将果蝇分成二组，其中一组注射磷酸缓冲生理食盐水（PBS），另一组则注射PBS加上细菌A｡在适当时间点采取样本进行基因X的表达量分析，结果如图甲所示｡该生又在第二次的实验中，利用一群野生型（具有正常X基因）及基因X缺陷型的果蝇，分析感染细菌A后1至6天期间所造成的死亡率，结果如图乙所示｡试回答下列问题：

语法填空

    Writing text messages while walking is dangerous. A study says it is more dangerous than texting while driving. Researchers found that there are more ____ (injury) to texting pedestrians(行人) than there are to texting motorists. Their report says walking is not as easy ____ we think. We must focus on many things at the same time to walk safely in a straight line. The researchers said that people forget how to walk ____ (proper), so dangerous things happen to them. They bump(撞) into walls and other people. They walk into cars, fall over things in the street, ____ even fall into holes.

    A professor said walking is a difficult action. There are several reasons ____ texting makes walking dangerous. ____ is that people cannot see the street. Another is that they focus on their phone keyboard instead of their feet. A final reason is that their minds are somewhere else—they are not thinking about ____ (walk) from A to B safely. The professor said over 6,000 people ____ (visit) his hospital last year because of texting. He said ____ worst cases are head injuries. When a pedestrian is tossed into the air he/she has nothing ____ (protect) the head. The damage can be serious.

下列选项与雅典民主政治的主要内容不相符合的是：

先算一算，再用正、负数分别表示盈利或亏损金额．

星星玩具店第二季度收支情况统计表

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