—Why do you look so worried?—Fred left the company half an hour ago. His work _______ unfinished since.
Please read the _______ on the bottle and take the right amount of medicine.
He suddenly appeared on ____ rainy night, which was ____ great surprise to us.
The Great Wall is ________ place that millions of people pay a visit there every year.
This is a very special flower and it can ________ a strong sweet perfume(香味) at night.
______ we know, the air quality in the city has improved over the past two years.