sitting duck

1. N-COUNT If you say that someone is a sitting duck, you mean that they are easy to attack, cheat, or take advantage of. 易受攻擊的目標; 容易受騙的人; 容易被人利用者[非正式]

Nancy knew she'd be a sitting duck when she raised the trap door. 南希知道，儅她擡起陷阱門時，她就會成爲被攻擊的目標。