ジョンはその問題を解こうと努力したが無理だった。

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

that (something or someone distant from the speaker, close to the listener; actions of the listener, or ideas expressed or understood by the listener); the; um...; er...; uh...

question (e.g. on a test); problem; problem (e.g. societal, political); question; issue; subject (e.g. of research); case; matter; question (i.e. doubt); public discussion; controversy; trouble; problem; inconvenience; difficulty

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to untie; to unfasten; to unwrap; to undo; to unbind; to unpack; to unsew; to unstitch; to solve; to work out; to answer; to dispel (misunderstanding, etc.); to clear up; to remove (suspicion); to appease; to dissolve (a contract); to cancel; to remove (a prohibition); to lift (a ban); to raise (a siege); to release (from duty); to relieve; to dismiss; to comb (out); to card; to untangle (hair)

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

great effort; exertion; endeavour; endeavor; effort

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

unreasonable; unnatural; unjustifiable; impossible; forcible; forced; compulsory; excessive (work, etc.); immoderate; to work too hard; to try too hard; irrational

be; is; indicates past or completed action; indicates light imperative