The relationship among sets proven by ? is named inclusion or containment. Equality amongst sets can be expressed with regard to subsets.B?n có th? ch?n th?c ??n s?n có ho?c ??a ra yêu c?u riêng, c?a ti?m s? t? v?n k? l??ng và ?i?u ch?nh linh ho?t ?? ?áp ?ng tr?n v?n mong mu?n c?a gia ch?.D?ch trong m?i ?ng d?ng B?t k? b?n ?ang dùng ?ng d?ng