— Why haven’t you asked her to come here?— She _______ an important experiment when I found her and she _______ it.
The research is so designed that once _______ nothing can be done to change it.
I felt it a great honour ______ to speak to you.
“What do you think made Mary so upset?” “_______ her new bike.”
When you’re learning to drive, _______ a good teacher makes a big difference.
“How do you deal with the disagreement between the company and the customers?” “The key ______ the problem is to meet the demand ______ by the customers.”