Expression: "Your duty as husband demands that you..."

[Tom]

Hi

Could you please look at this sentence? Why is there no article before "husband"?

[Yankee]

Hi Tom

The word husband has been used the same way you can use a general title or position:

- Your duty as mayor/manager/acting president/etc.
.

[Lost_Soul]

Hi, Amy

What if I want to say "Your duty as mayor of this city is...", do I need to put the article "the" before "mayor" ?

Thanks !

[Yankee]

Hi Alex

In this sort of structure, the word 'the' is optional.
Without 'the' there is more of a sense that 'this is a duty for any mayor'. With the word 'the', the focus is on the person who is now mayor and his/her specific duty.
.

[Klpno]

Hi Amy

I'd like to ask about article usage in the following sentence from the book I'm reading.

On his way over to the office, Vega saw that, as a sergeant, his wrist unit and HUD now had actual EVa access, and he saw that the 22nd was heading to B-5 the next day.

Can 'a' be dropped in this case, i.e. 'as sergeant' instead of 'as a sergeant'?