However, ___________ the technological difficulties of preparation, this material affords a further wide field of application(用途).
In those days John with his classmates _____ kept busy preparing for the exam.
As I have a meeting at four, ten minutes _____ all that I can spare to talk with you.
The writer and singer ______ here.
. No teacher and no student ______.
Nobody ______ seen the film. It’s a pity.