历史比较语言学在语言学史中的重要作用是什么？

什么叫做“历史比较法”？在汉语史的研究中怎样应用历史比较法？历史比较法的主要缺点是什么？

农民在先秦时期多称“臣”“人”“众”“野人”，秦汉时称“夫”“仆”，魏晋时称“田客”“部曲”，宋元时称“农户”“佃”。这种变化主要源于（）

对脑血管梗死的危险因素进行了病例对照研究，脑血管梗死患者100人，其中A型性格45人，非脑血管梗死患者100人，A型性格25人，A型性格的OR值为

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.

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。

为什么说梁启超是中国史学史的奠基人？

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。