fast、quick、rapid、swift、hasty、prompt、speedy与instant这些形容词均含有“快速”的意思。
fast : 常指人或物持续地高速运动，强调运动的方式。
- fast cars
速度快的汽车 - a fast swimmer
速度快的游泳者 - Computers are getting faster all the time.
计算机的速度在不断提升。 - The fast train (= one that stops at fewer stations and travels quickly) to London takes less than an hour.
到伦敦的快车需时不到一小时。
quick : 特指瞬时动作，强调动作敏捷迅速；也指匆忙的行为，而不暗示速度很快。
- It's a quick journey.
这次行程很短。 - I had a quick coffee and left the house.
我匆匆喝完咖啡，离开了家。 - I only had time for a quick glance at the paper this morning.
今天早上我的时间只够匆匆浏览一下报纸。 - He scored three goals in quick succession (= one after the other in a short time).
他短时间内连进3个球。 - Could I have a quick word (= speak to you for a short time)?
我可以简短地跟您说几句话吗？ - Quick as lightning (= very quickly), he snatched the book and ran out of the room.
他闪电般夺走了书，飞快地跑出房间。
rapid比fast和quick正式，常指运动本身，侧重速度惊人。所指动作可能是短暂的，也可能是持续的。
- The 1990s were a period of rapid change/growth.
20世纪90年代是一个迅猛突变／发展的时期。 - I was startled by a rapid movement to my left.
我左边什么东西猛地动了一下，吓了我一跳。 - His response to the accusation was rapid.
他对这种指责马上作出了回应。
swift : 正式用词，强调非常迅速，往往含动作轻快敏捷之意。
- The police took swift action against the rioters.
警方对暴动人员迅速采取了行动。 - Thank you for your swift reply.
感谢您的即时回复。 - The gazelle is one of the swiftest and most graceful of animals.
瞪羚是最敏捷、最优雅的动物之一。
hasty : 多指匆忙、草率或仓促的行动，着重缺乏深思熟虑。
- He warned against making hasty decisions.
他警告过不要仓促作出决定。 - Now let's not leap to any hasty conclusions.
现在我们不要仓促得出结论。 - We saw the rain and made a hasty retreat into the bar.
我们看见下雨了，于是就匆忙躲进酒吧里。 - I think perhaps we were a little hasty in judging him.
我认为我们对他的评价可能有点轻率。
prompt : 主要指动作迅速，毫不拖延，含“快得令人愉悦”的意味。
- They've written back already - that was a very prompt reply.
他们已经回信了——答复相当迅速。 - They're usually fairly prompt in dealing with enquiries.
他们回复咨询通常都比较快。 - Try to be prompt because we'll be very short of time.
尽量快点，因为我们时间很紧。
speedy : 指人或物或其运动、活动时，着重极度的快捷，多含匆忙意味。
- He's a very speedy worker.
他干起活儿来很麻利。 - We need to take speedy action/make a speedy decision.
我们需要迅速采取行动／迅速作出决定。 - Everyone is hoping for a speedy end to the conflict (= hoping that an end to it will happen quickly).
每个人都希望冲突可以尽快结束。 - We wished her a speedy recovery from her illness (= that she would get better quickly).
我们祝愿她尽快康复。
instant : 指某事很快发生或急待解决，含刻不容缓之意。
- In an instant her mood had changed.
顷刻间她的情绪就变了。 - The startled boy froze for an instant, then fled.
那个受惊的男孩愣了片刻，然后就逃跑了。 - "Stop that noise this instant (= now)!"
马上把那噪音停下来！ - I'll call you the instant (= as soon as) I get home.
我一到家就给你打电话。
