If _____ carefully, the experiment will be successful.
The doctor has worked with patients of this kind for eight years, so he knows what ________ in his job.
—Who telephoned you just now?— don’t know. I was about to answer the phone when it ________.
He recommended a reporter to us who has ________ outstanding talent for writing and is known for his sympathy for ________ poor.
This printer is of good quality. If it ______ break down within the first year, we would repair it at our expense.
Nobody believed his reason for being absent from the class ______ he had to meet his uncle at the airport.