如图（甲）是某物体运动的s﹣t图象，则图中能与之相对应的v﹣t图象是（　　）

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如图，直线a、b都与直线c相交，给出下列条件：①∠1=∠2；②∠3=∠6；③∠4+∠7=180°；④∠5+∠8=180°．其中能判断a∥b的条件是（　　）

阅读下列短文，从每小题的三个选项中选出最佳选项。

    Hello, I'm Ann. This is my family. There are five people in my family. My grandparents are old. They are teachers. My father is tall. He has a white shirt. He is a fireman. He is not afraid of fire. He can help people. He likes his job. My mother is tall and beautiful. She has long hair. She has a yellow skirt. She is a nurse. I don't have any aunts. What about you?

（Ⅰ）当点P在y轴上移动时，求点N的轨迹C的方程；

（Ⅱ）过点 $T\left(-\frac{1}{2}，0\right)$ 做直线l与轨迹C交于A，B两点，若在x轴上存在一点E（x₀，0），使得△AEB是以点E为直角顶点的直角三角形，求直线l的斜率k的取值范围．