在 TOEFL 中，每个句子都是经过 ETS 改编过的句子，比较规范，很少出现省略现象。一般主要在两种情况下会省略：如果定语从句的连接词 that 在从句里做宾语的话，一般会省略 that;另外一个比较常见的省略宾语从句的连接词 that。除此之外，个别情况下，比较结构中也往往会出现省略。大家在阅读的时候，要对此做适应性训练，一般就不会构成理解障碍。
图源网络，侵删
例 1.
Scientists felt that they could get an idea of how long the extinctionstook by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (Ir) it contained.
【解析】
在 they thought ( that ) they could determine the time 的宾语从句中，连接词 that 被省略掉了，在 they could determine the time ( that ) it took to deposit the clay 和 it took to deposit the clay by determining the amount of the element iridium (Ir) ( that ) it contained 中，因为 that 作定语从句的宾语，故这两个 that 也可以省略掉。
【 处理】
Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought ( that ) they could determine the time ( that ) it took to deposit the clay by determining the amount of the element iridium (Ir)( that ) it contained.
例 2.
Seldom is the weather more dramatic than when thunderstorms strike.
【解析】
than 相当于是一个准关系代词，它后面省略了主系表 the weather was dramatic而只保留了状语从句 when thunderstorms strike。
【 处理】
Seldom is the weather more dramatic than ( the weather was dramatic ) whenthunderstorms strike.
