26.【单选题】哲学上的物质范畴是对物质世界多样性和统一性所作的最高的哲学概括，它与自然科学关于具体的物质形态和物质结构概念之间的关系是（）。

There are many reasons for a flight ____.

There will be some air ____ in 10 minutes. Please return to your seat and fasten the seat belt.

Passengers are required to be at the airport 2 hours ____ departure.

Because of this, the economy is ____ to get worse.

The pilot was seriously injured and the ____ would take over.

A ____ of 20,000 people came to the concert.

What＇s the ____ rate between US dollar and Pound?

The customs officer caught a ____ dealer at the airport.

____ is an item that is not legally brought into the country.

She is very ____ and always cares about other people＇s feeling.