2010年考研英语二真题句子解析： Dr. Kroo and his team modeled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to assemble over Utah, assume an inverted V-formation, occasionally change places so all could have a turn in the most favourable positions, and proceed to London.

modeled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to assemble over Utah

条件从句中使用"were to assemble"而非"will assemble"，表示对将来情况的虚拟假设。主句使用"would happen"与之呼应，构成与将来事实相反的虚拟语气结构。这是典型的if条件句虚拟语气，用于表达假想的未来场景而非真实计划。

modeled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to assemble over Utah, assume an inverted V-formation, occasionally change places so all could have a turn in the most favourable positions, and proceed to London

整句包含多层嵌套：第一层，"what would happen"是宾语从句；第二层，"if three passenger jets...were to assemble"是条件状语从句嵌套在宾语从句内；第三层，"departing from Los Angeles, San Francisco and Las Vegas"是现在分词短语嵌套在条件从句的主语中；第四层，"so all could have a turn"是目的状语从句嵌套在条件从句的并列谓语中。这种从句套从句、从句套非谓语的混合嵌套造成了句子的高度复杂性。

three passenger jets departing from Los Angeles, San Francisco and Las Vegas

"departing from Los Angeles, San Francisco and Las Vegas"是现在分词短语，后置修饰名词"three passenger jets"，表示主动进行的动作，说明这些客机正从哪些地方起飞。这不是进行时态的一部分，而是作定语成分修饰前面的名词。

were to assemble over Utah, assume an inverted V-formation, occasionally change places so all could have a turn in the most favourable positions, and proceed to London

四个动词短语"assemble"、"assume"、"change places"和"proceed"通过逗号和最后的"and"形成并列关系，共同作为if从句的谓语部分。这些动词在语法地位上对等，依次描述假想场景中飞机的一系列动作，构成顺承递进的语义关系。