《史记·三十世家·郑世家》
四年的春季，郑国担心晋国来包围，公子如便立成公的哥哥做国君。
四年春，郑患晋围，公子如乃立成公庶兄繻为君。
In the spring of 564 BCE, Zheng was worried that Jin would come to besiege it, so Duke Ru set up Cheng's older brother Ji as the monarch.
<s>[INST] Kindly elucidate the central themes in this passage in English: 四年春，郑患晋围，公子如乃立成公庶兄繻为君。 [/INST] In the spring of 564 BCE, Zheng was worried that Jin would come to besiege it, so Duke Ru set up Cheng's older brother Ji as the monarch.</s>
Kindly elucidate the central themes in this passage in English: 四年春，郑患晋围，公子如乃立成公庶兄繻为君。
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In the spring of 564 BCE, Zheng was worried that Jin would come to besiege it, so Duke Ru set up Cheng's older brother Ji as the monarch.
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