题目

If you are afraid of the dark，it’s not a big deal．It’s perfectly normal to feel afraid After all，animals do too. “Fear matters，”says Karen Warkentin，an ecologist．“It’s a good thing，” she adds, “because fear makes you do things that keep you alive.”     Like kids，many animals experience fear and they respond to the feeling in variety of ways．A frightened turtle pulls its head and legs inside its shell．A  small fish will swim away when a big，hungry fish approaches．     Some animals respond to fear in ways you might not expect．The first一次函数y＝2x－4与x轴的交点坐标为(2，0)，则一元一次不等式2x－4≤0的解集应是 [　　] A．x≤2B．x＜2 C．x≥2D．x＞2