Another method is to place several cloth bags on top of each other in a box.

VOA: special.2009.09.29

I start off, either I take this path and carry on, or I take that path and carry on, but each box, if you like, gets touched exactly once.

程序开始后，或者采取这条路径然后继续，或者采取那条路径然后继续，但是每个图形，如果你喜欢这么说的话。

麻省理工公开课 - 计算机科学及编程导论课程节选

I start off, either I take this path and carry on, or I take that path and carry on, but each box, if you like, gets touched exactly once.

程序开始后，或者采取这条路径然后继续，或者采取那条路径然后继续，但是每个图形，如果你喜欢这么说的话。

麻省理工公开课 - 计算机科学及编程导论课程节选