sitting duck

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌsitting ˈduck (also sitting target) noun [countable]  ATTACKsomeone who is easy to attack or easy to cheat 易受攻击者；易受骗者 Out in the open, the soldiers were sitting ducks for enemy fire. 在毫无掩蔽的地方，战士们就成了敌人炮火的活靶子。

Examples from the Corpus

sitting duck• This makes the whole colony a sitting duck for a man with a gun.• Being left in front, Morley Street looked a sitting duck approaching the line but scrambled home.• Raskin was proceeding gingerly, aware that Macintosh was a sitting duck for cancellation.• She was a sitting duck out here all by herself!• We were like sitting ducks for pickpockets in the city.

ˌsitting ˈduck nounChineseSyllable  

attack to or is easy someone Corpus who easy

sitting duck
ˌsitting ˈduck (also ˌsitting ˈtarget) noun [countable]
someone who is easy to attack or easy to cheat:
    Out in the open, the soldiers were sitting ducks for enemy fire.

sitting duckBrE /ˌsɪtɪŋ ˈdʌk/ 🔊NAmE /ˌsɪtɪŋ ˈdʌk/ 🔊 (also ˌsitting ˈtarget) nouna person or thing that is easy to attack 易受攻击者；易被击中的目标