cH3-CH(C2H5)-CH(CH3)(C2H5)-CH3的写法有误
可能原题是这样的：cH3-CH(C2H5)-C(CH3)(C2H5)-CH3或cH3-CH(C2H5)-CH(CH3)C2H5-CH3
cH3-CH(C2H5)-C(CH3)(C2H5)-CH3：3,3,4-三甲基己烷
cH3-CH(C2H5)-CH(CH3)C2H5-CH3：3,4-二甲基庚烷