单项选择题 The importance of the distinction between a charter by demise and a charter party proper （）that under the former the master is the agent of the Charterer，not of the Shipowner.

单项选择题 The fact that it has become more onerous or more expensive for one party than he thought （）sufficient to bring about a frustration.

单项选择题 The fact that a charter-party（）more expensive for a party to perform is not sufficient to bring about its frustration