jack·knifeBrE/ˈdʒæknaɪf/NAmE/ˈdʒæknaɪf/verbpresent simple - I / you / we / theyjackknifeBrE/ˈdʒæknaɪf/NAmE/ˈdʒæknaɪf/present simple - he / she / itjackknifesBrE/ˈdʒæknaɪfs/NAmE/ˈdʒæknaɪfs/past simplejackknifedBrE/ˈdʒæknaɪft/NAmE/ˈdʒæknaɪft/past participlejackknifedBrE/ˈdʒæknaɪft/NAmE/ˈdʒæknaɪft/ -ing formjackknifingBrE/ˈdʒæknaɪfɪŋ/NAmE/ˈdʒæknaɪfɪŋ/[I]toformaV-shape. Forexampleifalorry/truckthatisintwopartsjackknifes, thedriverlosescontrolandthebackpartmovestowardsthefrontpart弯成 V 字形(如铰接货车失控时的弯折)