Tā měige zhōumò qù értóng fúlìyuàn zuò zhìyuànzhě.
She volunteers at the children's welfare institute every weekend.
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儿童福利院 is the formal, state term for what English calls an 'orphanage' - Chinese avoids 孤儿院 (orphanage) in official usage because many residents are abandoned children or disabled children with living parents, not strictly orphans.
