C7H14: C-C-C-C-C-C-C C-C-C-C-C-C C-C-C-C-C--C CC C-C-c-C--C C-C-C-C-C C-C-C-C--C C-C C C-C-C C-C-C-C--C C-C-C-C C C10H2可写出75个异构体; C20H42可写出36319个异构体。C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C7H14: C10H22可写出75个异构体; C20H42可写出366319个异构体