Answer:
A structure whose sub-units occur in a constant ratio and are arranged in a repeating pattern; the sub-unit can be individual atoms or a molecule.
Heterometallic systems Which employ multiple building units to produce extended structures.
And
Design and assessment of extended structures often require the generation of spatially variable earthquake motions to be used as multiple-support inputs.
Step-by-step explanation:
Such As A Polymer For Instance.
A type of extended structure that is made of many smaller, repeating sub-units in a chain; Although, The repeating sub-unit is a unique molecule. I Hope That This Answer Helps.