单项选择题
According to Papusek, the pleasure babies get in achieving something is a reflection of （）
A．a basic human desire to understand and control the world B．the satisfaction of certain physiological needs C．their strong desire to solve complex problems D．a fundamental human urge to display their learned skills
单项选择题 Papusek noticed in his studies that baby （）
单项选择题 According to the author, babies learn to do things which（）
单项选择题 The babies would "smile and bubble" at the lights because （）
