unless they succeed，the　yield gains of the green revolution will be largely lost even if the genes in　legumes that equip those plants to enter　into a symbiosis with nitrogen fixers　are identified and isolated，and even if　the transfer of those gene complexes，once they are found， becomes possible. (4)

除非他们能取得成功，不然的话，绿色革命的产量收益将在很大程度上损失殆尽，即使豆科植物中使这些植物有条件进入到与固氮细菌共生关系的基因可被辨识出来和分离开来的话，且即使这些基因综合体(gene complex)，一旦被发现之后，其移植得以成为可能的话。

难句类型：

复杂修饰、插入语

解释：

主句比较简单，而后面跟着的由and连接的两个表示让步的条件状语从句就相对复杂，第一个从句是用一个修饰主语的定语从句that equip those plants to enter into a symbiosis with nitrogen fixers把主谓隔开;第二个从句则运用了插入语once they are found把主谓隔开。

意群训练：

unless they succeed，the　yield gains of the green revolution will be largely lost even if the genes in　legumes that equip those plants to enter　into a symbiosis with nitrogen fixers　are identified and isolated，and even if　the transfer of those gene complexes，once they are found， becomes possible.