Contract Law - Kya Hua, Kya Hai?

Main to phir se Contract Law pad raha hoon, lekin yeh ek cheez hamesha se problem hai ki - when a contract is in writing but there is no writing for a part of it, kya hua? Bas, ek ekta se do ekton ke beech difference hain, lekin main samajh nahi pa raha hoon. Koi bhi ek ekta ko ignore kar sakta hai aur do ekton ke beech difference ko consider kar sakta hai. Lekin agar do ekton ke beech hi difference hai toh yeh ek ekta ka violation hai ya nahi? Yaar, main to exam ke do din bache hain aur phir bhi yeh cheez main nahi aya. Koi help karega?