Plural only, Stufe 2 style: write die, den, der, keine, keinen, meiner in full.
Every noun here is plural. Write the whole article — die, den, der, keine, keinen, meiner … — as well as the adjective ending. Each article gap shows its base word in grey.
Wer oder was? The subject — and after sein, werden, bleiben.
Wen oder was? The direct object — and after für, ohne, durch, gegen, um.
Wem? After mit, bei, nach, von, zu, aus, seit — and verbs like helfen, danken, gehören. Plural nouns add -n.
Wessen? Possession, and after wegen, trotz, während. Masculine and neuter nouns add -s or -es.
keiner is hardly ever used with a plural in the Genitiv, so this section uses meiner, unserer, seiner, ihrer — they take exactly the same endings as keine.
No case given here. Work out from the sentence which case each noun is in — the verb, the preposition, wo? or wohin? — then the ending.