1. All of the flowers now raised here have developed from those _______ in the forest.
A. once they grew B. they grew once C. they once grew D. once grew
2. In the office I never seem to have time until after 5:30 pm, _____ many people have gone home.
A. that B. which C. whose time D. by which time
3. Is this the reason _______ at the meeting for his carelessness in his work?
A. he explained B. what he explained C. how he explained D. why he explained
