1. The antonym of obstacle - convenient, unobstructed, smooth and unimpeded. Definition: something that blocks progress; To prevent from passing smoothly.
2. The sentence about obstacles: He has enough courage to cross the obstacles in front of him.
3. The natural danger of the Yangtze River was an insurmountable obstacle in ancient times.
4. The Red Army overcame many obstacles and reached the anti Japanese front line.
5. For junior high school students, the choice of words and sentences in English writing cannot be as easy as their mother tongue, and new words are a major obstacle.
6. The negotiation is about to end. Unexpectedly, the other side is making troubles again, raising some difficult problems and deliberately creating obstacles.