你可以通过一等邮件更快地寄信。

You can send letters by first ___class mail for quicker delivery.

在长途飞行中，我更喜欢使用商务舱机票。

I prefer to travel with a business ___class ticket on long flights.

超市保证所有产品都是甲级质量。

The supermarket guarantees that all its products are ___Class A quality.