By using an interatomic pair potential, which consists of a ledge-shape repulsive core and long-range Friedel oscillations, we investigate again the origin for the anomalous structures of liquid Ga, which is well known for a shoulder on the high-q side of the first peak in its static structure factor. We first examine our model by calculating dynamic properties and comparing with experimental data. Then, the liquid structures generated by MD simulations with our model at T=323K are analyzed. Though indeed found in our simulations, dimers with short bond-lengths are excluded as the possibility for the origin of the high-q shoulder. Instead, our results indicate that the high-q shoulder is resulted from some medium-range order, which is related to the structures beyond the first shell of the radial distribution function. The medium range order is caused by a cooperation between the ledge-shape repulsive core and the Friedel oscillations within a range of nanoscale.