To ask a question about the subject of a sentence, the word order is exactly the same as the word order for a statement. The form of the verb is exactly the same too.Look at this statement:
[s] John [v] met Maria at the station.
Now look at these two questions and answers:
[Q] Who did John meet?
[A] Maria (not the subject)
[Q] Who met Maria?
[A] John (the subject)
In the second sentence, we are asking about the subject of the sentence. Here are some more examples of subject questions:
Something happened in the kitchen.
What happened in the kitchen?
Someone knows a lot about physics.
Who knows a lot about physics?
Someone's writing is the best.
Whose writing is the best?
Some students are leaving on Monday.
Which students are leaving on Monday?
Hundreds of workers have been given a pay raise.
How many workers have been given a pay raise?
NOTICE: We do not use when or where in subject questions.