根据括号中所给提示用定语从句完成下列句子

a student ____will earn respect from others.(you work hard and achieve high grads in exams.)

you may look up a dictionary____when learning new words from english articles.(the dictionary has chinese definitions for english words.)

the policeman ____was my uncle.(i greetes a policeman just now.)

mr yang liwei's trip to outer space has realized the dream____.(the chinese people had a ream to go to outer space for years.)