Autumn
the season of the year between summer and winter, when leaves change color and the weather becomes colder 秋季，秋天 [主要用于英国英语中]
1. The autumn harvest is about to start.
秋收即将开始。
2. John is likely to be in London this autumn.
今年秋天约翰可能在伦敦。
3. It is bright and fresh in early autumn.
初秋的天气格外爽朗清新。
Fall
the season of the year between summer and winter, when leaves change color and the weather becomes colder 秋季，秋天 [主要用于美国英语中]
1. It took place in the fall of 1980.
它发生在1980年的冬季。
2. American people use the word fall to mean autumn.
美国人用fall来表示秋天。
3. Food prices lowered during the fall.
秋天食品价格下降了。
to drop down from a higher level to a lower level 落下，掉落 [不及物动词]
1. September had come and the leaves were starting to fall.
已经到九月了，树叶开始凋落。
2. One of the kids fell into the river.
其中一个小孩子掉进河里了。
3. The rain was falling steadily.
雨不停地下着。
【注意】
1. 在美国英语中，用fall表示秋天；而在英国英语中，用autumn表示秋天。
2. fall除了表示秋天，还可以用作动词，表示掉落。
3. 请注意fall作动词时过去式和过去分词的形式：fall - fell - fallen