First of all, Liu Biao was 66 when he died. During the Three Kingdoms period, the level of medical care was good. There are people who live long like Cheng Yu, Wang Lang and Liao Hua, and even people in their 80s. There are also people like Zhou Yu who died young. It's good to live to be 70. Liu Biao didn't support Lombardi much. He helped Zhang Xiu to resist Cao Cao before, and then nominally formed an alliance with Lombardi. At that time, Ma Chao, Han Sui, Sun Quan and Liu Zhang were nominally allies of Cao Cao, so Cao Cao had only two choices, taking Jingzhou or Hanzhong to fight Zhang Lu. Once Cao Cao attacks Jingzhou, it is difficult to confront Cao Cao with Jingzhou's strength. If he wants to defeat Cao Cao, he must rely on Liu Bei. And Liu Bei has shown the ability to defeat Cao Cao in the previous defending battle of Tancheng. Then once Cao Cao is defeated by Liu Bei, it is unlikely that Liu Qi and Liu Cong will succeed to the throne. So Liu is afraid of Cao Cao outside the table and Liu Bei inside. There is another problem, that is, when Liu Biao was appointed as Jingzhou Pastor by Dong Zhuo, he came to Jingzhou by himself. In order to get to the place smoothly, Liu Biao married the local Kuaijia and Cai Jia. The Kuai family and Cai family support their youngest son, Liu Cong, which may also lead to family infighting. But Liu Biao could not control the local army. In view of all these problems, Liu Biao finally died of anxiety.

Secondly, based on the above problems, if Liu Biao is not dead, he will definitely weigh the pros and cons. Kuai's family and Cai's family will not mess around before he dies. They also need Liu Biao. There are only two options left. One is that Liu Bei defeated Cao Cao. Then Jingzhou will be Liu Bei's sooner or later. Second, surrender to Cao Cao. If it were me, I would choose the latter. Because Cao Cao, after all, is under the banner of the Han Dynasty, and Cao Cao has always been kind to prisoners. For celebrities, Cao Cao still dare not kill them easily. For example, Yang Biao and Cao Cao were both tough, but Cao Cao didn't kill him, and it was too late to kill Kong Rong. Liu Biao was a celebrity in those days, and Cao Cao could not have killed him easily. If Liu Biao surrenders, there will definitely be senior officials.

In addition, before the official start of Battle of Red Cliffs, it was Cao Cao who led the vanguard to defeat Liu Bei in the sun. Liu Bei met Lu Su, who told Liu Bei that Zhou Yu's army was near Jiangxia. Zhou Yu has already sent troops to Jiangxia, Liu Qi. It can be seen that if Sun Liu does not form an alliance, Sun Quan is likely to attack Liu Biao, thus gaining some initiative in resisting Cao. This is consistent with the thinking of the Soviet Union during World War II. In fact, after Sun and Liu formed an alliance, Zhou Yu took an army. It is likely that Liu Qi's army will meet Liu Bei and suddenly attack Cao Jun near Jiangxia and defeat him. Cao Jun suffered another plague, and Cao Caocai decided to withdraw to the north of the Yangtze River, and Battle of Red Cliffs officially began.

In other words, if Liu Biao adopts this method of letting Liu Bei resist Cao, he should also consider whether to at least cede Jiangxia to. After all, everyone knows that it is not advisable to hit Cao Cao and Sun Quan at the same time.

Finally, Liu Biao was written into The Romance of Three Kingdoms. In fact, Liu Biao is still a relatively capable person. If he is fighting for the world, then his talent is far from enough. If he just kept Jingzhou, he seemed to have done well. At least as you said, he didn't have time to finish this difficult multiple-choice question, but chose this just right time to die. The reflection says that Jingzhou was levied in July and Liu Biao died in August. It can be seen that many people think that it is possible that Liu Biao was scared to death.