`@` Nguyên
`1`. My sister works as manager at a shop which sells woman clothing.
`2`. The bridge that connects two islands was constructed five years ago.
`3`. I studied Korean at a training center of which the equipment was innovative and modern.
1. WHO
….. N (person) + WHO + V + O
2. WHOM
…..N (person) + WHOM + S + V
3. WHICH
….N (thing) + WHICH + V + O
….N (thing) + WHICH + S + V