Absorption of overheads

Sir,
Although I have watched lectures attentively but
In example 1 (pg 33) We absorbed overheads using units since there was only one product
In Example 2 We absorbed using labour per hours $ basis..

So will there be questions asking to absorb cost using materials per kg $ basis?

And if there would be question like that can you please give me examples of overheads associated with Materials..

I am clear with overheads associated with labour i.e repair maintenance staff, supervisors, Factory Cleaning
But I am confused with materials overheads