danger—endanger

　　large—enlarge

　　ex-：former ( and still living )

　　minister—ex-minister

　　wife—ex-wife

　　extra-：outside；beyond

　　curricular—extracurricular

　　ordinary—extraordinary

　　fore-：in advance，before；in or at the front

　　arm—forearm

　　warn—forewarn

　　il-：( used before l ) not

　　legal—illegal

　　literate—illiterate

　　im-：( used before b，m，p ) not

　　moral—immoral

　　possible—impossible

　　in-：not

　　direct—indirect

　　sensitive—insensitive

　　infra-：below in a range；beyond

　　red—infrared

　　structure——infrastructure

　　inter-：between；among

　　change——interchange

　　national——international

　　intra-：inside，within；into

　　city——intracity

　　department——intra-department

　　ir-：(used before r)not

　　regular——irregular

　　responsible——irresponsible