As the plates drifted, they may have diverged, which(指代前面一句话) was associated with the spread of the seafloor, or they may have converged, which(指代前面一句话) resulted in collision, subduction, and mountain building。

**系表倒装

主系表结构 变成 表系主 结构成为系表倒装只限于介词词组在句首时

1、My hometown lies in Jilin province。

In Jilin province lies my hometown。

2、A,B,C….are among the species of seabirds。

Among the species of seabird are A,B,C…。

3、副词性从句 =状语从句

引导词 when/though/while/although……

结构 when+s’+v’+adj/v-ing/v-ed,SVO。

When he was young, Jack was always beaten by his father。

省略的条件 s’=S v’=be

省略 When young, Jack was always beaten by his father。

省略 Other(联系同一类的名词，也就是说前面提到了chemical defenses) possible chemical defenses, while (they are 省略) not directly toxic to the parasite, may inhibit some essential step in the establishment of a parasitic relationship. For example, glycolproteins in plant cell walls may inactivate enzymes the degrade cell walls.