如何界定西方经济学？ 试述西方经济学的研究对象和研究方法。

Every deliberate act of wrongdoing by the master or any of the crew against the ship or cargo，without the authorization or privity of the Shipowner or his agent，is（）.

A salvor may be（）the whole or part of the payment due under Salvage Convention to the extent that the salvage operations have become necessary or more difficult because of fault or neglect on his part or if the salvor has been guilty of fraud or other dishonest conduct.

Vessels must be（）valid certificate of nationality or certificated of registry or license.

产品A的边际转换率会随着A的产量增加而（）。

学习西方经济学的目的是什么？借鉴西方经济学应注意什么问题？

边际收益递减律（Law of diminishing marginal returns）

根据微观经济学的观点，以下哪一项是产品转换曲线：（）

边际收益产品（Marginal revenue product）

边际产品转换率（Marginal rate of product transformation）

Marginal revenue product（of an input），（ MRP） （一种投入的）边际收益产品

什么是网络产品的边际效用？简述网络经济下边际效用递增现象的原因。