FIRST - we inhale oxygen using our nose or mouth., THEN - the air goes down the trachea to the lungs., NEXT - in the lungs, blood absorbs the oxygen., FINALLY - we exhale Carbon Dioxide., IMPORTANT! - The diaphragm helps us inhale and exhale.,

排行榜

視覺風格

選項

切換範本

恢復自動保存: ?