冠詞a後面加什麼詞性

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

我做了那麼多工作，可什麼也沒得到。

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

你要參加這個大學教程，就需要通過三科高級證書考試。

A number of measures were taken to alleviate the problem.

採取了一系列措施緩解這個問題。

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

她自從得到了那份工作，變得判若兩人。

A free trade agreement would be advantageous to both countries.

自由貿易協定對兩國都會有利。