Tough luck: in Perl 5, you can't ignore an alternation without the somewhat esoteric and not always available regular expression? : modifier.

实在不幸：在Perl 5中，如果不使用某些深奥而且不是永远可用的正则表达式？：修饰符，您就不能忽略选择。

youdao

"A collection devoted to dogs and to the American Kennel Club may seem somewhat esoteric, " Mr. Savino said.

WSJ: A Library With a Pedigree | American Kennel Club Research Library | By Joanne Kaufman

It also spanned the development of The Economist from a small, influential but somewhat esoteric publication to a much larger, more commercially conscious undertaking.

ECONOMIST: A remarkable colleague