I don’t know who invented_____digital camera, and it’s really _____ most useful invention.

______ did you go last Saturday— I went to the zoo.

The police found that the house ____ and a lot of things ____[ ]

The number of various educational programs is increasing, _______ important roles have been realized by more and more people.

Walmart, one of the largest supermarket chains, ________ some of its stores open 24 hours on Mondays through Saturdays.