As a doctor, you can bear to see your patient once vigorous living the painful, limited life. On the other hand, you hate to be the one to decide to let nature take its course .

A、 come to a natural end
B、 be on its course
C、 be responsible for
D、 come to on its route

【正确答案】 A

【答案解析】解析：take its course．意为“任其自然发展，按常规进行”。