understanding, comprehension / appreciation

explanation

explanation; commentary

understand, comprehend / appreciate

question, problem on homework etc. / a question; a matter (of time etc.) / a problem (something that needs to be dealt with); a trouble / an issue; a matter

to read (look at and interpret written text) / to read (speak aloud written text) / to infer; to speculate / to count

reading / (figuratively) understanding of something, speculation about something

impossible to understand, utterly confused

(informal) no problem

unthinkable, out of the question