(3)
比較A、B所受重力的大?。?img class="mathml" src="http://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmrow%3E%3Cmsub%3E%3Cmi%3EG%3C%2Fmi%3E%3Cmtext%3EA%3C%2Fmtext%3E%3C%2Fmsub%3E%3C%2Fmrow%3E%3C%2Fmath%3E" style="max-width:100%;vertical-align: middle;">
(選填“<”“=”“>”).