The answer, in my opinion, is the second sentence, "The coach who is an expert in the sport explained the revised rules to us". Here, the "Who is an expert", is presumably the nonessential clause.
usually either somber or very proud of his country
Answer: he disappears by putting the ring on
D. to establish a uniformity of presentation that enhances communication
Answer:
Man I hope he can walk soon, can he walk right now?
Explanation: