Having checked the doors were closed, and ________ all the lights were off, the boy opened the door to his bedroom.
Jane is one of the students in the class ______ have ever been to China.
I arrived half an hour earlier ______ I had time to talk with him before the meeting.
He asked me ______.
While ______ in Scotland, he made friends with the natives there.
I will never forget the classmates ______ I studied with.