To take advantage of a weak point or opening; to exploit a vulnerability.
小偷就是趁着家里没人，才乘虚而入偷走了贵重物品。
The thief took advantage of the empty house to break in and steal valuables.
Era:
Ancient
Frequency:
Story:
In 817 AD, Emperor Xianzong of the Tang Dynasty appointed Li Su, a general known for his wisdom and bravery, as the Jiedushi (military commissioner) of Tanghe and three other prefectures. His mission was to attack Wu Yuanji, the son of the rebellious Huai-Xi Jiedushi.
Li Su first won over several surrendered generals, including Ding Shiliang, Li You, and Li Zhongyi.
Then, seizing an opportune moment when the enemy was unprepared, he stealthily entered Caizhou, captured Wu Yuanji alive, and quelled the rebellion.
Next Idiom