I’m sorry I can’t help ____ the flowers, because I’m busy preparing for the singing competition ____ tomorrow.
A mysterious illness, referred to as “ a typical phenomena”, has been brought under control, the government said on Wednesday, ______ no cause of it has been made public.
Before leaving home, make sure to turn off the electricity, lock the door, ______ the windows open.
I can _____ some noise while I’m studying, but I can’t stand very loud noise.
The idea for the new machine came to Mr. Baker ______ to his invention recently.
Professor Liu has ________ teach psychology since he came to the Central China Normal University.