keen、acute、sharp与shrewd这些形容词均有“锐利的、敏锐的、机敏的”之意。
keen : 多指对复杂艰深的事物或问题有敏锐的观察和敏捷的理解。
- a keen sense of smell
灵敏的嗅觉
acute : 侧重感觉敏锐，能分辨出一般人难以觉察的细微区别。
- acute eyesight/hearing
敏锐的视觉／听觉 - an acute sense of smell
灵敏的嗅觉 - a woman of acute intelligence/judgment
机敏聪颖／有敏锐判断力的女性
sharp : 指人头脑精明、敏锐或机警。
- Birdwatchers need to have sharp ears and eyes.
观鸟者必须有敏锐的耳朵和眼睛。 - She has a sharp eye for a bargain.
她非常善于发现便宜货。 - Our new director is very sharp.
我们的新主任非常精明。 - She manages to combine a sharp mind/intellect with a sympathetic manner.
她既有机敏的头脑，又能做到善解人意。 - He was a man of sharp wit/sharp-witted man who always spoke his mind.
他是一个思维敏捷、说话从不拐弯抹角的人。 - The play was full of sharp one-liners.
这出戏充满了机智风趣的俏皮话。 - He may be old but he's still as sharp as a tack.
他可能是上年纪了，但仍然思维敏捷。
shrewd : 指有头脑，善于判断分析，精明过人。（延伸阅读： 小词详解 | shrewd）
- He was shrewd enough not to take the job when there was the possibility of getting a better one a few months later.
他很聪明没有接受那份工作，因为几个月后他有可能会得到更好的工作。 - She is a shrewd politician who wants to avoid offending the electorate unnecessarily.
她是一个精明的政治家，想避免不必要地得罪选民。 - It was a shrewd move to buy your house just before property prices started to rise.
在房地产价格开始上涨之前购买房子是个明智之举。
