你吃过这道菜吗？

Nǐ chī guò zhè dào cài ma?

Have you eaten this dish before?

这个字我已经学过了。

Zhège zì wǒ yǐjīng xué guò le.

I've already studied this word.

小时候我学过一点儿钢琴，但是后来就忘了。

Xiǎoshíhou wǒ xuéguò yìdiǎnr gāngqín, dànshì hòulái jiù wàng le.

When I was little I learned a bit of piano, but later I forgot it.