name the common serving line of ban thung pho junction railway station and bukit mertajam railway station ?
SELECT DISTINCT var_uri where brack_open dbr_Ban_Thung_Pho_Junction_Railway_Station dbo_servingRailwayLine var_uri sep_dot dbr_Bukit_Mertajam_railway_station dbo_servingRailwayLine var_uri brack_close