A good teacher should leave some time for the students to _________ the knowledge.
The _______ price will save you one dollar for each dozen.
The student corrected his paper carefully, _______ the professor's suggestions.
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.