GJ:=HHV(M20,180);
DJ:=LLV(M20,180);
GGL:= GJ/C;
DGL:= DJ/C;
X1:介於(GGL,0.8,1.2)和GJ & lt;& gtM20
X2:介於(DGL,0.8,1.2)和DJ & lt& gtM20