—Who____ it be that is knocking at the door? —It ____ be Father, but I’m not sure.
The general manager’s _____ directions confused the staff, who didn’t know what to do.
. Being hard-working is of the highest __________ to becoming successful.
— Did you see _________ jacket on the playground just now? — Is it _________ new one and very cool?
—Why are you standing here? —I’m waiting for Shirley. She will be back _____.
. By the year 2020 scientists _____ a lot of research on AIDS.