Peter can play ______ piano and ______ football.

Who____ it be that is knocking at the door? — It ____ be Father, but I’m not sure. [ ]

ea for the new plan came to his mind, ______ to hisexperiment in the lab.

Fred chose a sunny sloping bank witha thick growth of bushes, and ________ there a nice little hen-house

that they may eventually reduce the amount of labor needed on construction sites by 90 per-cent.