It has a gate on it and that gate is in open or close state depending on whether a ligand is present or not.

在这个通道上有个门,这个门是打开还是关闭,取决于配体到来与否

耶鲁公开课 - 生物医学工程探索课程节选

So for each student the tutor builds a model of that Student's current state what the computer thinks they Know and doesn't know, and tries to present the student options that best meet what the tutor thinks are the student's need at that moment.

因此辅导系统会给每个学生,创建一个模型记录他们当前的学习状态,判断他们已经掌握和还不了解的知识,然后给出此时导师认为,最符合他们需要的选择。

麻省理工公开课 - 媒体、教育、市场课程节选