After the new technique was introduced, the factory produced _______ tractors in 1988 as the year before.
The three of us ______ around Europe for about a month last summer.
Experiments of this kind _______in both the U.S. and Europe well before the Second World War started.
Robert is said________ abroad, but I don’t know what country he studied in.
We live in an age ________ more information is available with greater ease than ever before.
Tom took a taxi to the airport, only _____ his plane high up in the sky.