What is the answer to this riddle-

साथ-साथ मैं चलती हूँ,
पर पकड़ नहीं सकते हो तुम।
अंधियारा छाते ही देखो,
गायब होती मैं गुमसुम।

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Saath-saath mai(n chaltii huu(n,
par pakar nahii(n sakte ho tum.
andhiyaaraa chhaate hii dekho,
gaayab hotii mai(n gumsum.

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I come along with you,
but you cannot catch me.
you can see, as soon as darkness falls
I disappear quietly.

Answer- परछाई (parchhaaii)- shadow   f.

shadow