sentence analysis

[1364]

Hi all,
Is it ok to analyse this sentence“The wheel, the loom,the plow,and metalworking were basic.”
in this way?

“The wheel, the loom,the plow,( complete sub), and metalworking(compound sub) were basic(complete predicate).”
So my problem is that whether we should consider this sub as complete one or compound complete subject??

Thanks in advanced

[Tdol]

Is there a reason to separate 'metalworking'?

[1364]

Is there a reason to separate 'metalworking'?

in our grammar book wrote that this is compound complete subject so i just wanna know the reason ?
"i guess maybe it's because of 'metalworking' as compound subject "
thanks again