我会弹吉他但是弹得不是很好用英语怎么说

"I can play the guitar, but not very well" 是一种常见的表达方式。

"Can" 是动词"能"的过去式，表示"会"的意思。 "But" 是连词，意思是"但是"。 "Not very well" 是副词短语，表示"不是很好"。

例句：

I can play the guitar, but not very well. (我会弹吉他，但是弹得不是很好。)
I can speak Spanish, but not very well. (我会说西班牙语，但是说得不是很好。)
I can swim, but not very well. (我会游泳，但是游得不是很好。)