I'm trying to convey the sentence "我不会好好发音四个声调" But that more directly translates as "I cannot pronounce four tones well" which is a bit ambiguous... that begs the question, which four tones? I'm sure anyone I say this to would understand but it doesn't sit well with me. In English it is easy, I'd say "I cannot pronounce the four tones well" which implies the existence of exactly 4 tones, all of which I have trouble pronouncing. So far I have not seen a Chinese equivalent?
The definite article has no equivalence in Chinese. Its functions, however, can be found in Chinese.
- Something previously mentioned or known
He is a murderer. 他是个杀人犯。(杀人犯 is a murderer, a man that has commited murder. 个 is like the indefinite article.)
He is the murderer.
By using nouns inherently specific.
他就是凶手。(凶手 is the murderer , it cannot be used without context. 他是个凶手(incorrect))
By using demonstratives: 这/那/这些/那些/此/彼
- Something unique or identified by the speaker, terminologies.
I cannot pronounce the four tones well.
我发不好四声。(平上去入(tradition)/阴阳上去(modern mandarin), as a whole isn't referred as 四个声调)
Particularly, these sets of similar things are usually referred without measure words.
Unique things, such as the sun, the moon... are referred exactly its name (Actually the definite article is unnecessary semantically)
As for "I want to go to a/the park", it's not hard to appreciate that 我想去公园。 already fully conveys the two possible interpretation, depending on the listener.
The is rarely explicitly expressed in Chinese. Like the comments mentioned below your question, the closest equivalent is going to be a combination of 这 (this) or 那 (that) and the appropriate measure word. You might notice Chinese ESL speakers struggle with definite articles in English and that is because similar usage is not found in Chinese.
As for the specific sentence you’re trying to write, you’re better off with saying something more general like: