On these first two examples of dependent clauses within the sentence. Where is the main clause if you remove the dependent clause?
What the girl did was not very helpful.
The trophy goes to whoever wins the race.
You may play outside/ until the street lights come on. (This works on it's own logically followed by a dependent clause).
You could be told ''You may play outside''. But not ''the trophy goes to'' without saying who it goes to.
What do we call this contrast between these sentences. The first two require the dependent clause but the last example could work either way.