Hoặc
a) CH3 – CH(CH3) – (CH3)C(C2H5) – CH2 – CH3
b) CH3 – C(CH3)2 – CH(CH3) – CH(CH3) – CH2 – CH2 – CH3
c) CH3 – C(CH3)2 – CH(CH3) – CH2 – CH2 – CH3.