---What do you think of the dinner in Mr Brown's?---Oh, great! We have never had a better one. It's a dinner of twenty ____.

At the meeting, the professor presented a new __________ to foreign languages.

The driver can adjust the heating in winter and the air conditioning in summer to suit his own _____.

Even the experienced doctors dare not carry out the operation because of the         of failure.

As the quality of the city’s air continues to give rise to ______, the residents are encouraged to set off fewer fireworks.