彼の振る舞いは

his behavior

→ 彼
phrase Rare #22,387
his behavior は marks “his behavior” as the topic; the phrase is usually followed by a comment about it.
JA: 彼の振る舞いはいつも丁寧だ。
EN: His behavior is always polite.

彼の振る舞いは奇妙である。

His behavior is strange.

彼の振る舞いは賞賛に値する。

His conduct is worthy of praise.

彼の振る舞いは批判にも値しない。

His behavior isn't even worthy of criticism.

彼の振る舞いはしばしば非難の対象になった。

His behavior was often the subject of criticism.

彼の振る舞いは見事だった。

His performance was remarkable.

彼の振る舞いは尊敬に値する。

His conduct is worthy of respect.

今日の彼の振る舞いはとても変だ。

His behavior today is very strange.

彼の振る舞いは紳士の振る舞いであった。

His behavior was that of a gentleman.