what are common contractions in classical chinese?
http://en.wikipedia.org/wiki/Contraction_%28grammar%29#Chinese gives the following (just copied it in):


諸 = 之乎 (In some rarer cases 諸 can also be contraction for 有之乎. 諸 can be used on its own with the meaning of "all, the class of", as in 諸侯 "the feudal lords.")
焉 = 於之 (於之 is never used; only 焉.)
旃 = 之焉 (Rare.)
爰 = 于之 (Rare. The prepositions 於, 于, and 乎 are of different origin, but used interchangeably (except that 乎 can also be used as a final question particle).)
然 = 如之
云 = 曰之
弗 = 不之
勿 = 毋之 (弗 and 勿 were originally not contractions, but were reanalyzed as contractions in the Warring States period.)
耳 = 而已
盍 = 胡不 (胡 is a variant of 何.)
與 = 也乎 (Also written 歟.)
邪 = 也乎 (Also written 耶. Probably a dialectal variant of 與.)
夫 = 不乎 (夫 has many other meanings.)
奈何 = 若之何