In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years....In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years.为什么第一个空不填冠词,第二个空填a,怎么不填

In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years....In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years.为什么第一个空不填冠词,第二个空填a,怎么不填
In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years....
In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years.为什么第一个空不填冠词,第二个空填a,怎么不填the?

In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years....In 1778,Banks was elected___president of the Royal Society,___position he held for 42 years.为什么第一个空不填冠词,第二个空填a,怎么不填
第一个空是被推举为某职位担任者而不是一个某职位担任者,不能后加冠词,第二个是一个什么职位（后加定语从句限定）不是特指哪个职位…多读书有语感多做笔记就ok了…其实大多数的英语用中文直接去理解是不好理解的

表示头衔的词一般前面都不加冠词，而第二个空你可以从意思上理解，“一个他任职了42年的岗位”。