输出只有一个大写字母的行

输出只有一个大写字母的行

这样的正则怎么写啊? 今天才开始学正则,不好意思 ~

比如有
Bytes from the converted String
Are written Until
reached. If the precision
Is omitted, it is taken
To be Infinite, So all bytes up to The end of the

只能输出 Is omitted, it is taken
因为其他行的大写字母多于1或小于1
if ($line =~ tr /A-Z// == 1)
多谢~~有问题再向你请教~