关键

crucial point / crux / CL:個|个[ge4] / key / crucial / pivotal

mountain pass / to close; to shut; to turn off / to confine; to lock (sb) up; to shut (sb in a room, a bird in a cage etc) / to concern; to involve

key (on a piano or computer keyboard) / button (on a mouse or other device) / chemical bond / linchpin