Use an index card as your bookmark.

用一张索引卡做书签。

Sign your name on the index card.

在图书卡上签上你的名字。

Or take out an index card.

或用一张指数卡片。

You'll never loose an index card again!

你再也不用担心丢失那些生词卡片了！

In fact, you can do it with a single index card.

事实上，你可以通过一张索引卡片来做到这些。