ドアを開けようとしました。

N5 ドア doa door

N4 開 kai / hira.ku, hira.ki, -bira.ki, hira.keru, a.ku, a.keru open, unfold, unseal

N5 〜ます masu Used at the end of verbs, polite present or future form, makes the sentence more polite N4 〜し shi Indicates multiple reasons or qualities, connects clauses or adjectives, means besides that, and also N5 〜を o Marks the direct object of an action, appears before the verb, shows what receives the action N5 〜と to Indicates company, quotation, natural condition, complete list, or direct connection between elements N5 〜よ yo Sentence ending particle adding information to listener, emphasizes statement, expresses certainty or warning