在英语中,介词at,on与名词构成介词短语作连系动词be的表语时,具有“进行”意义,通常有几下几种:1.be+at/on+动作名词。这一结构通常表示“从事某种活动”或“在干某事”,相当于该动词的现在分词。如:①A group of students are at play on the playground.=A group of student In English, the preposition at, on, and noun constitute predicative phrases for the conjunction verb be with the meaning of “conducted”, usually with several kinds: 1.be+at/on+ action nouns. This structure usually means “to engage in certain activities” or “to do something”, which is equivalent to the present participle of the verb. For example: 1A group of students are at play on the playground.=A group of student