We have a high regard for Mr. Smith because he always tries to _____________his principles.
─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?