In 1900, the energy derived from burning petroleum was only four percent ______ of coal.

Mrs. Smith locked both the front and the back doors before she went to bed______thatsomeone might steal into the house at night.

Notallbirdscanfly,______doallbirdsbuildnests.

On arriving home, the boy told his parents about all the ______ which occurred in his dormitory.

Iwasshockedbythenumberofpeoplewhoseemedtohavenothingbettertodowiththeirtimethan______toknowfishbetter.