英汉词典

In addition to the uses shown below, at is used after some verbs, nouns, and adjectives to introduce extra information. At is also used in phrasal verbs such as ‘keep on at’ and ‘play at’.
除下列用法外，at用于某些动词、名词、形容词后以引出附加信息。at还可用于keep on at, play at等短语动词中。