It is said that ____ wool produced in Australia is of ____ high quality.
Drivers are warned that it is dangerous to talk on the phone while________.
The Great Wall is _________________ tourist attraction that millions of people pour in every year.
They began to consider what use could ___ the natural resources(资源).
____ number of students in our class ____ larger than that in theirs.
He refused to ___ to the terrible weather only at the last moment because he had no choice.