（）是生产重要基本有机化工原料乙烯、丙烯、丁二烯、苯、甲苯、二甲苯（通称“三烯三苯”）的原料。

假设A＝〝计算机〞，B＝〝等级考试〞，结果是“计算机等级考试”的表达式是（ ）。

Project（71）is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

Project ______is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

● Project（71）is an uncertain event or condition that, if it occurs, has a positive or a negative effect on at least one project objective, such as time, cost, scope, or quality.（71）

 ______ twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.

A declaration made by the Master before a PRC Consul，giving particulars regarding heavy weather or other incidents which may have caused damage to the vessel or cargo，through no fault of the vessel，her officers，or crew is a(n)（）.

化工生产厂房的耐火等级按生产类别分（）。

It will be a relief over the death of a friend or a relative if the friend or relative dies from ______.

A mark or place at which a vessel comes under obligatory entry，transit，or escort procedure is know as（）.

丙烯腈毒性等级为甲A类。

对某化工厂清釜工体检发现肝、脾大者多例，肝癌1例，此化工厂最可能生产（）