Describe when the Period of Disunion occurred.

 The Period of Disunion lasted from about 420 to 589 AD.  The disunion started when the Han Dynasty collapsed.  During this time, China remained divided into different dynasties ruling the North and South. The disunion finally came to an end in 589 AD when the Sui Dynasty came into power and reunited China.  The northern  ruler Yang Jian was the one to unify China creating the Sui Dynasty.  

1. where does the energy of a nuclear power plant come from?

d) political bosses should not hold office