Because the molecules in liquids are so densely packed together , the average time between collisions is a picosecond or less .
Because the molecules in liquids are so densely packed together , the average time between collisions is a picosecond or less .
由于液体中的分子很密地积聚在一起，所以，两次碰撞之间的平均时间间隔只有一微微秒或者更短些。