《新五代史·列传·梁臣传第十一》
刘知俊反叛，攻陷长安，刘郡、牛存节等人进攻他，很久不能攻克。
刘知俊叛，攻陷长安，刘掞、牛存节等攻之，久不克。
Liu Zhijun rebelled and captured Chang'an. Liu Qun, Niu Cunji and others attacked him, but they couldn't capture him for a long time.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 刘知俊叛，攻陷长安，刘掞、牛存节等攻之，久不克。 [/INST] Liu Zhijun rebelled and captured Chang'an. Liu Qun, Niu Cunji and others attacked him, but they couldn't capture him for a long time.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 刘知俊叛，攻陷长安，刘掞、牛存节等攻之，久不克。
user
Liu Zhijun rebelled and captured Chang'an. Liu Qun, Niu Cunji and others attacked him, but they couldn't capture him for a long time.
assistant