例句1：If you are part of the group which you are addressing, you will be in a position to know the experiences and problems which are common to all of you and it'll be appropriate for you to make a passing remark about the inedible canteen food or the chairman's notorious bad taste in ties. (2002 Text1)
【结构分析】本句包含由and连接两个并列分句。第一个分句主干为you will be in a position，不定式to know the experiences and problems 做定语，修饰position，其中which引导定语从句，修饰the experiences and problems。第二个分句为it'll be appropriate for you to …，其中it作形式主语，真正的主语为不定式to make a passing remark about…
例句2：Just as on smoking，voices now come from many quarters insisting that the science about global warming is incomplete, that it's OK to keep pouring fumes into the air until we know for sure。(2005 Text2)
【结构分析】本句的主干是voices come from…，现在分词短语insisting…作voice的后置定语，insiste后接两个 that引导的宾语从句，分别为that the science about global warming is incomplete和that it's OK to keep pouring fumes into the air until we know for sure，第二个that从句中，it是形式主语，真正的主语由不定式短语充当，until we know for sure为时间状语从句。
例句1：Further more，it is obvious that the strength of a country's economy is directly bound up with the efficiency of its agriculture and industry, and that this in turn rests upon the efforts of scientists and technologists of all kinds. (2000-72)
【结构分析】本句主干为it is obvious that…，其中it是形式主语，真正的主语为and连接的两个that引导的名词性从句that the strength of a country's economy is…和that this in turn rests…第一个主语从句中，代词its指代 country's;第二个主语从句中，this指代 efficiency of its agriculture and industry。
例句2：It's not obvious how the capacity to visualize objects and to figure out numerical patterns suits one to answer questions that have eluded some of the best poets and philosophers。(2007Text2)
【结构分析】本句中It为形式主语，真正主语是其后how引导的主语从句，how the capacity suits one to answer questions，两个不定式结构to…作capacity的后置定语， questions后面的that引导定语从句，关系代词that在从句中作主语。
例句1：The explanation for insensitivity to smell seems to be that the brain finds it inefficient to keep all smell receptors working all the time but can create new receptors if necessary。(2005完形)
【结构分析】本句的主干为主系表结构The explanation…seems to be…，表语部分由that引导的表语从句充当。在此从句中，使用了find it +adj.+to do 结构，it是形式宾语，真正的宾语由不定式短语充当。but并列了the brain后的两个谓语finds it inefficient to keep…和 can create new receptors if necessary。