请懂英语的朋友帮忙看一下这个英语语法是怎么回事?怎么会有两个be动词?这句话是林肯说的：When an end is lawful and obligatory,the indispensable means to it is are also lawfull and obligatory.为什么有两个be动词啊?

What makes life dreary is the want of motive. When an end is lawful and obligatory, the indispensable means to it are also lawful and obligatory.
中文意思：
如果一个目的是正当而必须做的,则达到这个目的的必要手段也是正当而必须采取的.
你是不是记错了，这句话is是多余的
因为 means 单复数同型，但在此指methods,是复数，所以只用are就行了。

When an end is lawful and obligatory,the indispensable means to it are also lawfull and obligatory.
如果一个目的是正当而且必须要达到的,则达到这个目的所采取的手段也必须是正当的。
the indispensable means是主语，to it 作定语，be动词are作谓语，
lawfull and obligatory作表语，
“the indispensable means to it is are also lawfull and obligatory”是主系表结构

说明转的时候错了

第二个分句应该没有is。整句话翻译过来是：当一个结局是合法且必要的，那么达到它（所使用的）必不可少的手段也是合法且必要的