Many of my students have been struggling with oral English practice. It occurs to them that it's almost an impossible mission unless they try to recite scripts as doing a poem at secondary school.
If watching the clip below, you may find the interviewee from the interview speaks as fluently as a English-native speaker. And please bear in mind that his mother-tongue is German, although whose syntax is rather similar to that of English because the root of both languages is originated from Germanic one.
One thing I'm sure is that without intensive practice he wouldn't have spoken as confidently as he is doing at the moment. From linguistic point of view, there are many different complex sentences he's using like subject /object/adverb relative clauses, complements, adverbial subordinate clauses and counterexample conditionals. All of those add up to his crystal clear logic that is so easy to comprehend.
One peculiar thing I notice after watching the interview is how many Chinese students or tutors are used to speaking 'unless' on daily basis. I'm afraid the answer is definitely 'No'. Thus my advice is that any English learner whose final objective is to master the lingua franca has to and must take advantage of English logic otherwise they could be a dilettante only.