题目

阅读下面短文, 从短文后的选项中选出可以填入空白处的最佳选项。选项中有两项为多余选项。. When we meet with something we're not familiar with or something frightening, our brain and body start making changes to help prepare us for the unknown. Dr. Kerr says, For some people, choosing to be scared can be fun.What good is fear?. It tells a person to hide, run away, or defend oneself. Faster heartbeat and breathing send more blood and oxygen to the muscles so they are ready when they are needed. Stress chemicals can make a person more alert.Our memories also h一列简谐波在t=0.2s，时刻波的图像如图（甲）所示，x=0的质点的振动图像如图（乙）所示，由此可知： A.波沿x轴负方向传播，波速V=10m/s B.波沿x轴正方向传播，波速V=10m/s C.t=0.2s时刻，质点c向y轴负方向运动 D.t=0.3s时刻，质点b的位移y=10cm