A1
used to ask at what time something happened or will happen
Dictionary examples:
When did the cat eat my homework? (0.0)
When did you become so tall? (0.0)
When will my socks stop disappearing? (0.0)
When did he leave? (4.8)
"I did tell you about it." "When? I don't remember." (4.9)
When's your birthday? (6.5)