Misty has the option of purchasing one of three products: Brand A, Brand B, or Brand C. Each costs ten dollars. If she decides that Brand A meets her needs best, then the opportunity cost of this decision is
A.
Brand B plus Brand C.
B.
twenty dollars.
C.
Brand
D.
Brand B or Brand C, depending on which is considered the highest-value alternative forgone.
【简答题】实验:测小车的平均速度。 如图3所示,斜面长2.4米,测得小车从斜面顶端运动到底端所用的时间是6秒。如果在斜面的中点装上金属片,测得小车从斜面顶端运动到金属片的时间为4.8秒。请将测量数据填入表中,并计算出小车通过全程的平均速度 v 1 和通过上半段的平均速度 v 2 。 (1)小车从斜面顶端运动到底端过程中,小车做________(选填“匀速”或“变速”)运动。 (2)根据上表的数据,小车通过斜...