Twin-bottle nursing bottle

A nursing bottle comprising:

• an outer bottle having a mouth at the top;
• an outer cap fastened to the mouth of said outer bottle through a screw joint to hold a nipple, said outer cap comprising an elongated horizontal slot and a vertical inside groove;
• an inner bottle disposed inside said outer bottle, said inner bottle comprising a bottle body having a mouth at the top, a cup-like inner cap fastened to the mouth of the bottle body of said inner bottle, said cup-like inner cap comprising a cap body, a locating ring spaced around the cap body of said cup-like inner cap and retained between the mouth of said outer bottle and said nipple by said outer cap, and radial ribs connected between the cap body and locating ring of said cup-like inner cap, the cap body of said cup-like inner cap having a top mouth disposed at an elevation not lower than the topmost surface of said locating ring;
• and
• switch means received within said outer cap between said nipple and said locating ring and controlled to let a first fluid in said outer bottle or a second fluid from said inner bottle flow into said nipple for suction by the baby or to let both said first and second fluids flow into said nipple simultaneously.