4. The docto has operated Tom since 10 o'clock
=tom
5.A man returnned the keys to me
= The keys
6.they made jean cloth completely from cotton in the 18th century
=jean cloth
7.my cousin will meet you at the station
= you
8. He can't repair my bike
= My bike
9 we can solve the problem
=The problem
10. You must do this exercise carefully
=this exercise