For instance, in most legal systems, while an oral contract is legally binding, a written contract is preferred.

比如，在很多法律体系中，虽然口头约定是有法律约束力的，但是人们还是倾向才用书面约定。

Disputes over an oral contract will involve one person's recollection of the contract versus another person's.

关于口头合同的争议将涉及一个人对合同的回忆与另一个人的回忆。

First, to take a contract an oral contract as a right contract and secondly to take an oral contract as something that is flexible and can change over time because circumstances change.

首先，将口头合同视为一种权利合同，其次，将口头合同视为一种灵活的东西，可以随着时间的推移而变化，因为环境的变化。