Ellen Q. answered 01/08/21
College and High School Chinese for Classes and Tests (AP& IB)
Chinese verbs have no morphological changes. Present perfect in English could be presented by prepositional phrases, adverbs, particles. “Since “could be translated into 从…开始/起 or 就;就…了,or 已经…了. The following sentences all could be proper expression of the sentence: I have known her since we were both 2 years old.
我俩同岁,我两岁开始就认识她了。
我两岁时就已经认识她了,我俩一样大。
我打两岁起就认识她,我俩一般儿大。( Often used in spoken language)
我们俩从两岁起就认识了。
我们从两岁开始就认识了。
我们两岁时就互相认识。
The first three sentences more emphasize on “I have known her”. The other three are more like free translation. Hope it helps.