It was not until 1920 ______ regular radio broadcasts began.
I met several people there, two of _____were foreigners.
He told me the news_____, believe it or not, he had earned $1 000 in a single day.
Who do you guess _____ to the station to meet her?
After ____ seemed like hours he came out with a bitter smile.
According to the rules, students must not _____ their books during examinations.