Personally, I see this ratings/feedback thing only useful for mentors to know if a student is abusive and/or a help vampire, if he is willing to learn and put some effort on the process or not, etc, to be able to dedicate mentoring time to someone who will really appreciate it and will benefit from this.

Slimy things did crawl with legs Upon the slimy sea.

The equivalent weight of an element or compound is that weight equivalent in reactive power to one atomic weight of hydrogen.

He chanced upon the definition when leafing through the dictionary.