In Russian, I can put a colon before a subordinate clause that clarifies something or gives a reason to what is said in the main clause. For example, I can write something like this,
There was a bit of a problem: John barely understood what she was trying to communicate due to her thick French accent.
Paul had a very satisfied look on his face: he got an A for his test.
We call those conjunction-less complex sentences. What do you do in English in such cases? What can I do in such cases? Can I likewise replace conjunctions (like 'because') with punctuation marks in English? (note, I want to construct a complex sentence, please don't suggest breaking it down to two sentences)