We should encourage our students _____ hard instead of ____ too much time playing games.

Mr. Smith will move into his new house next Sunday, ________ it will be completely finished.

The runners________ several times ________their positions on the starting line, otherwise they will be kicked out

udents were studyingin____________classroom when, all of ____________sudden,the lights went out.

We will be shown around the city: schools, museums, and some other places, _____ other visitors seldom go.