We must be off _____ It’s eight o’clock already

You ought to have called him yesterday．—Yes，I know I．

Tom realized that he ________ his physicsbook at home when he reached school．

Tom, don’t _________ to bring my English book to me.- OK, Mary. I can.

I feel a bit nervous since this is the first time that I _______ to give a lecture to so large an audience till now.