1-甲基-2-乙基环己烷 cyclo- 2-ethyl-1-methyl cyclohexane CH3 CH3 CH2CH3 顺-1-甲基-2-乙基环已烷 反-1-甲基-2-乙基环已烷 cis- trans- 1 1-甲基-2-乙基环己烷 2 3 4 5 6 cyclo- 2-ethyl-1-methyl cyclohexane 顺-1-甲基-2-乙基环己烷 反-1-甲基-2-乙基环己烷 cis- trans￾CH3 CH2 CH3 H H CH3 CH2 CH3 H H