either are used to (use to) produces (produce) so and (but) rust corrodes (does rust corrode) or their (its) as well as (but also) not the only substance
या भनौँ यो यति स्वाभाविक हुन्छ कि कसैले यसमाथि प्रश्न उठाउनु जायज नै ठान्दैन वा यसलाई निरपेक्ष ठान्छ ।