4.the firm is sending me to newyork. i work for this firm.
=> I work for this firm which is sending me to New York.
5. i was sitting in a chair. it suddenly collapsed.
=> I was sitting in a chair which suddenly collapsed.
6.His girlfriend turned out tobe an enemy spy.he trusted her absolutely.
=> He trusted his girlfriend who turned out tobe an enemy spy absolutely.
7.opposite our school there is a nice park.there are some beautiful flowers in this park.
=> There are some beautiful flowers in a nice park opposite our school.
8.the boy is his son .he is with him.
=> The boy who is with him is his son.
9.the vendor's wife has just had the first baby.she has been married for 10 years.
=> The vendor's wife who has been married for 10 years has just had the first baby.
10.Yesterday i met Harry.he works near here now.
=> Yesterday I met Harry who works near here now.
11.the wedding took place last friday.only members of th family were invited to it.
=> Only members of the family were invited to the wedding which took place last friday.