Will the English teacher please analyze the structure of this sentence?

This sentence structure is inappropriate, please add it.

Although the British police use the joke adverbial clause, it mainly means that sometimes it is even impossible to tell whether it is a joke or not.

Although the British introduce the method of describing polite subjects to the object (adverbial clause) called passing jokes.

That leading word is sometimes a predicate, just like its formal subject, and it can even be judged whether it is a joke or not (object clause)!

If the subject of introducing it is the predicate of a verb, is it a joke?

Although the British way of telling jokes is polite, it means that sometimes it is even difficult to tell whether it is a joke or not!