2,4-二甲基-3-乙基庚烷 2,4-dimethyl-3-ethyl heptane 3-ethyl-2,4-dimethyl heptane CH3-CH CH 2,6-二甲基-3-乙基庚烷 CH一CH2-CH-CH-CH CH 2-甲基3-环戊基戊烷? 2,4-二甲基-3-乙基庚烷 2,4-dimethyl-3-ethyl heptane 3-ethyl -2,4-dimethyl heptane 7 6 5 4 3 2 1 2,6-二甲基-3-乙基庚烷 CH CH CH3 CH3 CH3 CH CH2 CH2 CH3 CH2 CH3 2-甲基-3-环戊基戊烷 CH3 CH2 CH CH CH3 CH3