Chuyển các câu sau đây sang bị động : a) She had finished her report soon. b) A group of students have met their friend at the railway station. c) Why didn’t they help him ? d) They made him work all day. e) The detective saw the woman putting the jewelry in her bag. f) The terrorists made the hostages lie down. g) Police advise drivers to use an alternative route. h) She helps me do all these dificult exercises