it's this paper mend with a plastic cover and there's all these black magnetic particles here.

它是用这种纸以及一种塑料覆在上面,这里还有一些黑色磁性粒子。

哈佛公开课 - 计算机科学课程节选

it's this paper mend with a plastic cover and there's all these black magnetic particles here.

它是用这种纸以及一种塑料覆在上面,这里还有一些黑色磁性粒子。

哈佛公开课 - 计算机科学课程节选