--- What made Bill so angry?--- _____. His girl friend promised to come at 8:30, but she hasn’t come yet.
We’retalkingaboutthepianoandthepianist_____wereintheconcertweattendedyesterday.
Thefreezingpointisthetemperature__________waterchangesintoice.
Don’t talk about such things _______ you are not sure about.
Hurry! The train _______. You know it _____at 8:30am. .
With the help of high technology, more and more substances _________ in the past years.