例句1 In the remaining cases, the working group found the studies had weaknesses in design and content which affected the validity of their conclusions - they lacked a control group, for example, or used faulty statistics. （剑 14 Test 4 Passage 3）
1）结构分析 层次一： 主句：the working group found the studies had weaknesses in design and content 修饰①：which...conclusions【which定从，修饰weakness】 修饰②：－.... statistics【破折号解释weakness】 修饰③：in........cases【in介短状语，修饰主句，表地点】
例句2 Usually, scientists don' t know exactly how disasters such as a tanker accidentally spilling its whole cargo of oil and polluting huge areas of the ocean will affect the environment until after they've happened. （剑 14 Test 4 Passage 3）
1）结构分析 层次一： 主句：scientists don' t know exactly how disasters will affect the environment 修饰①：such as ....ocean【such as介短定语，修饰disasters】 修饰②：until......happened【until状从，修饰主句，表时间】
例句3 If the vehicle can do some or all of the driving, it may be possible to be productive, to socialize or simply to relax while automation systems have responsibility for safe control of the vehicle. （剑 15 Test 1 Passage 2）
1）结构分析： 层次一： 主句：it may be possible to be productive 修饰①：to socialize or simply to relax【to do同位语，解释productive】 修饰②：while......vehicle【while状从，修饰主句，表伴随】 修饰③：if.........driving【if状从，修饰主句，表条件】
