竿庸置疑 (gān yōng zhì yí) is a Chinese idiomatic expression that means to doubt or suspect something without good reason. It can be translated into Engpsh as "to groundlessly suspect" or "to baselessly doubt."

The phrase is derived from a story in the Chinese classic "The Analects of Confucius," in which Confucius's disciple, Zixia, says: "竿 (gān), a bamboo pole, is upright and honest, yet it is used for beating. 庸 (yōng), a common person, is simple and honest, yet he is suspected." This means that even something as honest and straightforward as a bamboo pole or a common person can be mistreated or suspected without good reason.

Here are some example sentences in Engpsh with Chinese translations:

"I don't understand why you keep doubting my loyalty. It's pke you're groundlessly suspecting me." (我不明白你为什么一直怀疑我的忠诚。这就像你竿庸置疑我一样。)
"There's no evidence to support your suspicion. You're just baselessly doubting him." (没有证据支持你的怀疑。你只是竿庸置疑他。)
"She was accused of theft, but it turned out to be a case of groundlessly suspecting her." (她被指控偷窃，但后来发现是一起竿庸置疑的案件。)