下列语句中，反映长江流域已成为我国古代经济重心的是（）

长江中下游地区是我国古代重要的农业区，从（）时代开始称为中国的经济中心。

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（）.

（）, or drum is used for hauling in or letting out the wires or ropes which will fasten the ship to the shore.

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.

The （） is used for hauling in or letting out the wires or ropes.

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

中国古代经济重心东移南迁的原因？

简述中国古代经济重心南移的主要原因。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

下列选项中，反映长江流域已成为我国古代经济中心的诗词是（ ）。

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。