I would have expected '一顆' and the particle '了'.
There is something known as
measure words, which in Mandarin includes '顆', 棵', '個', '杯', '盅', '罈', and so on. You may find the thread which follows interesting:
Chinese is a tonal language — 中文是 <個 / 種> 聲調語言.
If we were to narrowly define what exactly a measure word is, in Mandarin, then neither '個' nor '種' in the sentence above would be counted since there would be no loss of meaning if they were removed. That is, it is perfectly natural to say, '中文是聲調語言', which means the same. '個' and '種' are used as measure words in sentences like '山裏有三個土匪' and '我的老師只會說一種語言'.
When should I use [an] indefinite article in Chinese and when not?
I am not a grammarian, so I may be wrong. In my mind, indefinite articles in Mandarin are measure words in its broadest sense (in combination with the numeral '一', if any) that
- can be removed from a sentence at no or little expense of the meaning, or
- are obligatory but not given emphasis.
For example, '我最近好像喜歡上了一個女孩'. This can be translated into English as, '
I have probably been into a girl recently'. But, if we were to remove '一個', it would mean, '
I have probably been into the girl recently' or '
I have probably been into girls recently', which makes sense only if the speaker expects readers to have already known about the girl, or the speaker has not been into girls, perhaps been into men, until recently, and either case it would sound somewhat unnatural. And it is not particularly important how many girls he is referring to. So '一個' is an indefinite article in this sentence.
In contrast, '一種' in '我的老師只會說一種語言' is not an indefinite article, by definition. That sentence means, '
My teacher can speak one language only'. Note that we have used '
one'.
