在轻绳的两端各拴一个小球, 一人用手拿着绳的上端的小球站在三层楼的阳台上, 放手让小球自由下落, 两小球相继落地的时间差为Δt,如果站在四层楼的阳台上, 同样放手让小球自由下落, 则两个小球相继落地的时间差将( )
A:不变
B:变大
C:变小
D:无法判断
Take the advice ________ is given by Dr. White.
平行四边形的面积是____
Alan is as as Lucy in their class.