The past two years _______ a sharp rise in oil price，which adds to the burden of auto transportation industry.
| A．witnessed | B．witnesses | C．is witnessing | D．has witnessed |
People _______ in the city do not know the pleasure of country life.
| A．live | B．to live | C．lived | D．living |
The _______ price will save you one dollar for each dozen.
| A．reduce | B．reducing | C．reduced | D．reduces |
The student corrected his paper carefully, _______ the professor's suggestions.
| A．follow | B．following | C．followed | D．being followed |
He went from door to door, _______ waste papers and magazines.
| A．gathering | B．gathered | C．gather | D．being gathered |
. _______ the office, the foreign visitors were shown round the teaching building.
| A．Having shown | B．Showing | C．Has shown | D．Having been shown |