Fairly, pretty, quite, and rather can all be used to modify adjectives and adverbs, but are all less strong than very. Rather and pretty are the strongest of these words and are the closest to very. Pretty, in this sense, is informal. Therefore, if you said to someone, 'Your work is pretty good' or 'Your work is rather good', they would be more likely to be pleased that if you said 'Your work is quite good' or 'Your work is fairly good'. However, rather is commonly used with words indicating negative qualities. I was feeling rather sad. It is the only one of these words that can be used with comparatives, and with too. Global warming could be rather worse than we think it will be... He was becoming rather too friendly with my ex-boyfriend. Quite is slightly stronger than fairly, and may suggest that something has more of a quality than expected. Nobody here's ever heard of it but it is actually quite common.

fairly, pretty, quite 和 rather 都可用来修饰形容词和副词，但都没有 very 语气强。rather 与 pretty 是这几个词中语气最强、与 very 最接近的词。pretty 用于此意是非正式的用法，因此如果对某人说 Your work is pretty good (你干得很好)或 Your work is rather good (你干得相当好), 比说 Your work is quite good (你干得很不错)或 Your work is fairly good (你干得还不错), 更让听者感到高兴。但 rather 通常与带有负面意义的词连用，如 I was feeling rather sad (我觉得很难过)。rather 也是这些词中唯一能与比较级和 too 连用的词。如：Global warming could be rather worse than we think it will be (全球变暖可能比我们想象的还要严重些)。He was becoming rather too friendly with my ex-boyfriend (他和我的前男友有些亲密过头了)。 quite比 fairly 语气稍强, 表示某物比预料中更具某种品质。如：Nobody here's ever heard of it but it is actually quite common (这儿没人听说过它，但它实际上很常见)。