汽油馏分中主要存在的环烷烃是（）环烷烃。

下列关于烷烃性质的叙述中，不正确的是（）。

以下关于云南农业大学优秀团学干部评选资格的叙述中，正确的有（）

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。

下列关于细胞中化学元素的叙述，正确的是（）

关于卤族元素的化学性质下列叙述正确的是

逻辑运算符（AND、NOT、OR）的运算顺序是AND→OR→NOT。