"爱问长问短的人" can be translated into English as "a person who is always asking a lot of questions" or, more idiomatically, "a nosy person" (though "nosy" has a slightly negative connotation implying prying into others' affairs beyond simple curiosity).
For a more neutral and literal translation emphasizing inquisitiveness:
"A person who loves to ask numerous questions"
"An inquisitive individual who asks a lot"
The choice depends on context and tone. If you want to focus on the act of asking many questions without judgment, the first options work; if implying a bit of over-curiosity, "nosy" fits but carries a negative nuance.