问答题 The course of history is never smooth. It is sometimes beset with difficulties and obstacles and nothing short of a heroic spirit can help surmount them. A mighty long river sometimes flows through a broad section with plains lying boundless on either side, its waters rolling on non-stop for thousands upon thousands of miles. Sometimes it comes up against a narrow section flanked by high mountains and steep cliffs, winding through a course with many a perilous twist and turn. A nation, in the course of its development, fares likewise. The historical course of mans life is just like a journey. A traveler on a long journey passes through now a broad, level plain, now a rugged, hazardous road.