Which of the following reaction are substitution?

CH3CH2COOH + CH3OH = CH3CH2COOCH3 + H2O
CH3CH2OH = CH2CH2 + H2O
CH3CCH + HBr = CH3CBrCH2
CH3CH2CH2CH3 + Br2 = CH3CH2CH2CH2Br + HBr

The following reaction is substitution:

CH3CH2CH2CH3 + Br2 = CH3CH2CH2CH2Br + HBr