1.Peter is the tallest boy in my class.(改为同义句）
Peter is (taller)(than)(any)(other)(boy) in my class.
2.Mary might be a doctor when she is older(就a doctor提问）
(What)might Mary (be) when she is older.
3.Mary wants to be a doctor.I want to be a doctor,too(把两句话合并成一句话）
Mary wants to be a doctor and(so)(do)(I)