Chen　[2016a,　2016b]　studied　global　dynamics　of　the　Filippov　systems　＜(x)double　over　dot＞　+　(alpha　+　beta　x(2))(x)over　dot　+　x　+/-　sgn(x)　=　0,　respectively.　To　study　the　global　dynamics　of　＜(x)double　over　dot＞+(alpha+beta　x(2))(x)over　dot　+/-　x　+/-　sgn(x)　=　0　completely,　since　the　dynamics　of　＜(x)double　over　dot＞+(alpha+beta　x(2))(x)over　dot-x-sgn(x)　=　0　is　very　simple,　we　are　only　interested　in　the　global　dynamics　of　＜(x)double　over　dot＞+(alpha+beta　x(2))(x)over　dot　-　x　+　sgn(x)　=　0　in　this　paper.　Firstly,　we　use　Briot-Bouquet　transformations　and　normal　sector　methods　to　discuss　these　degenerate　equilibria　at　infinity.　Secondly,　we　discuss　the　number　of　limit　cycles　completely.　Then,　the　sufficient　and　necessary　conditions　of　existence　of　the　heteroclinic　loop　are　found.　To　estimate　the　upper　bound　of　the　heteroclinic　loop　bifurcation　function　on　parameter　space,　a　result　on　the　amplitude　of　a　unique　limit　cycle　of　a　discontinuous　Lienard　system　is　given.　Finally,　the　complete　bifurcation　diagram　and　all　global　phase　portraits　are　presented.　The　global　dynamic　property　of　system　＜(x)double　over　dot＞+(alpha+beta　x(2))(x)　over　dot-x+sgn(x)　=　0　is　totally　different　from　systems　＜(x)double　over　dot＞+(alpha+beta　x(2))(x)+x　+/-　sgn(x)　=　0.