felicitous

他在婚礼上的致辞恰到好处，赢得了宾客们的掌声。

His ___felicitous speech at the wedding won applause from the guests.

他在紧张的面试中一个恰如其分的笑话打破了冰冷的沉默。

His ___felicitous joke broke the icy silence during the tense job interview.

她为婆婆的七十五岁生日挑选了一条恰到好处的丝巾。

She made a ___felicitous choice of a silk scarf for her mother-in-law's seventy-fifth birthday.