Chalk marks began to appear on the brown linoleum .
粉笔标记逐渐出现在棕色的油地毡上。
It is these , fossilised , that form rocks such as chalk andlimestone .
也正是这些物质，形成了诸如白垩和石灰石的化石。
Plus , tutorials are a nice excuse to break away from the dull side of a designer 's life to have fun , yet you can still chalk up a tutorial as education .
