______ you need any help, you can always phone me at the office.

 ______ it be true that we will have to wait for 3 hours in a line to get into the French Pavilion in the Expo Site?

— Did you go to the lecture by the visiting professor?— No. I ______ it, but I've been busy taking care of my grandma in hospital these days. 

If he _______ the opportunity at that time, he would be the new department manager now.

The boy         the first prize, but he was so careless as to make a foolish mistake.