Only when they were put in prison and lost freedom(自由) _________ its importance.
He went from door to door, _______ waste papers and magazines.
. _______ the office, the foreign visitors were shown round the teaching building.
With winter _______ on, it's time to buy warm clothes.
Deeply _______, I thanked her again and again.
_______ how to do the homework, I went to ask my teacher for help.