'What time' vs. 'At what time.

Since the question 'What time did you come?' gives the answer 'I came at one o'clock', grammatically,

the preposition 'at' should be in question form.

 

Thus, 'At what time...?' is OK and from a prescriptive grammatical standpoint is correct,

but most people say 'What time...?'.

 

Full correct grammar:

• At what time did you come? 'I came at one (o'clock)' or 'At one (o'clock).'

 

Short version:

• What time did you come? 'One'.

 

 

english.stackexchange.com/questions/298592/what-time-vs-at-what-time