K2 is the number of sensitive elements containing 2-methyl 1,4-hetero-cluster clusters and non-nucleus at the C3 position. It can be divided into K2(10), K2(20), K2(35), K2(40 )Wait. K2(35) is the digital chain K2 with 35 carbon elements on the carbon chain of the carbon element; the text K2(235) is also an individual methylpentene-7, which is based on its wide heterogeneous chain with 7 different The name of the pentadiene chain.