First question

Question

In the first question (at least russian version) there is wrong answer. Reg. exps are for "checking if the email has right format" but not for "checking if the current email exists". I repeat, this issue exists in russian version and probably not in english.

Answer 1

if I recall correctly, the question (in English) is asking "for which task are regex's not appropriate", so one of three will be wrong/the answer.

Answer 2

exists? where?

Answer 3

In the first question to regular expressions.

Answer 4

where?