Starting a question with What or Which can be a bit tricky, but one of the basic rules or guidelines will have to do with the content of the question. The word What can be used to begin most any...
The editor noticed that the word Corigendum was spelt incorrectly, so he inserted a Corrigendum slip in the next print.When he found more than one error, he produced Corrigenda slips.
If you mean to include alone in the sentence here is a few examples:I was walking alone.Joe was alone on Christmas da.Sometimes its easier to work alone.I like to be alone.