I think this software is of little use to your work. It is really a ________ of money.
─What are you reading, Jane? ─Some books on ________ education, I’m now interested in ________ education of young people.
He stayed there for quite a long time, during ________ time he learned much spoken English.
The man showed us so heavy a stone ________ no man can lift.
Some pictures of the river brought the days back to the old ________ they swam in it.
Is this research center ________ you visited the modern equipment last year?