L is for layers.Wearing loose, lightweight clothes, one layer on top of another, is better than wearing a single heavy layer of clothing.

VOA: special.2009.12.23

The thing is for these sorts of experiments there is a lot of control, so something that's a square in one movie will be a triangle in another movie; something that's on the top in one movie will be on the bottom in another movie.

此类实验需要控制许多因素,来保证某物在一部影片中以正方形呈现,而在另一部影片中以三角形呈现,某物在一部影片的上方呈现,而在另一部影片的下方呈现

耶鲁公开课 - 心理学导论课程节选

Adobe is shaped into bricks that are laid one on top of another and used as a low cost way to build walls and houses.

VOA: special.2009.01.12

They were placed one on top of another in a circular shape.

VOA: special.2011.05.18