Thank you, Dan. Yes, I guessed it later.:))

I don't understand your question. Is this a poem with lines that rhyme? I don't know a meaning for "CG" that makes sense here. In the United States, it is traditional to give students letter grades, and a common system is A, B, C, D, and F. (There is no "E"). In this system, "C" is often the lowest satisfactory or "passing" grade; a student with all "C" grades might be allowed to graduate.

Does it mean satisfactory grades?