冠词a后面加什么词性

　　I didn't get a red cent for all my work.

　　我做了那么多工作，可什么也没得到。

　　You need three A levels to get onto this university course.

　　你要参加这个大学教程，就需要通过三科高级证书考试。

　　A number of measures were taken to alleviate the problem.

　　采取了一系列措施缓解这个问题。

　　She's a changed woman since she got that job.

　　她自从得到了那份工作，变得判若两人。

　　A free trade agreement would be advantageous to both countries.

　　自由贸易协定对两国都会有利。