almost 指在程度上相差很小，差不多。
nearly 与almost含义基本相同，侧重指数量、时间或空间上的接近。
about 常可分almost和nearly换用，但about用于表示时间、数量的“大约”时，实际数量可能多也可能少。
approximately 多用于书面语，指精确度接近某个标准以致误差可忽略不计。
around 多用于非正式场合，常见于美国英语。
roughly 指按精略估计，常代替about。
参考例句
1. That was the one you nearly swallowed! 差点被你吞下的就是这个球？
2. The salesman showed her nearly all the hats in the shop. 该店员几乎将店中所有帽子都拿给她看了。
3. You played a few as well. You often spun the ball so much; it nearly burnt a hole through my racket. 你也打了一些很好的球。你常常将球旋转得很厉害，它几乎可以在我的球拍上烧一个洞。
英英解释
adv.
1. (of actions or states) slightly short of or not quite accomplished
2. in a close manner
