It is not without melancholy that I wander among my recollections of the world of letters in London when first, bashful but eager, I was introduced to it. It is long since I frequented it, and if the novels that describe its present singularities are accurate much in it is now changed. The venue is different. Chelsea and Bloomsbury have taken the place of Hampstead, Notting Hill Gate, and High Street, Kensington. Then it was a distinction to be under forty, but now to be more than twenty-five is absurd. I think in those days we were a little shy of our emotions, and the fear of ridicule tempered the more obvious forms of pretentiousness.
1) Then it was a distinction to be under forty - 这句中的distinction前为何可加a？ 查牛津词典，好像应该是：
[U] the quality of being excellent or important 出色；杰出；卓越
a writer of distinction 出色作家
[sing.] the quality of being sth that is special 特质；特征；十分出色
She had the distinction of being the first woman to fly the Atlantic. 她十分出色，是第一个飞越大西洋的女子。
所以，麻烦老师解说一下这里的distinction的解释和使用方法。
2) 顺便请教老师，查词典有时会看到一个单词[sing.]（用单数），那样这种用单数的[sing.]可否加a? 还是只能加the或零冠词？
3) tempered the more obvious forms of pretentiousness - more 是修饰形容词的比较级，还是限定数目的呢？怎么样区别呢？
Then it was a distinction to be underforty, but now to be more than twenty-five is absurd.
【翻译】当时年龄不到四十岁就被看作了不起的人物，现在过了二十五岁就让人不可思议了。
这是英语“抽象名词具体化”的表现—— 在有的抽象名词前加冠词a，就能让这个抽象名词具体化，转化为可数名词。此状况在英语中不少、非常容易见到。这里，distinction 原本是抽象名词“出色；杰出；卓越；独一无二”，加了 a 之后成为可数名词，指具体的人：“一个了不起的人；一个独一无二的人”。
比如：
help 帮助→a help 助手
pleasure快乐→a pleasure开心的事
success成功→a success成功者或成功的事
failure失败→a failure失败者或失利的事
beauty漂亮→a beauty美人或漂亮的事物
surprise惊奇→a surprise让人惊奇的事
honor荣幸→an honor让人感到荣耀的人或事
comfort舒适→a comfort让人感到安慰的人或事
shame羞耻→a shame让人感到可惜（耻）的人或事
regret遗憾→a regret让人感到遗憾的事
joy开心→a joy让人开心的人或事
danger危险→a danger让人感到危险的人或事
pity遗憾→a pity让人遗憾的人或事
youth青春→a youth年轻人人
disappointment 失望→adisappointment让人失望的事
