出处：按学科分类—语言、文字 中国对外翻译出版公司《汉英成语词典》第156页（206字）
理直气壮地说个不停，例他理由充足，说起话来自然就振振有词了。
He based his arguments on well-founded reasoning and solid grounds， which enabled him to speak plausibly and at great length．