It is for a person in his position to make such a mistake.
It was not until she came to see us ____ her mother was ill in bed.
The boy wanted to ride his bicycle in the street, but his mother told him _____.
---- I’ll be away on a business trip. Would you mind looking after my cat? --- Not at all. ____.
---- Do you mind my taking this seat? ---- ____.
It was not until 1920 ____ regular radio broadcast began.