Don’t answer the phone when the cell phone is being charged, for it ________ be very dangerous sometimes.
It was because of the bad weather __________ the football match had to be put off.(推迟)
It is the first time that I _______ this kind of moon cake.
There was ______ time _____ Chinese used foreign oil.
While ___ along the street, I met an old friend of mine.
Your time should be made full use of ________ English well.