A.
研磨剂涂得太薄?xml:namespace prefix="o" ns="urn:schemas-microsoft-com:office:office">?xml:namespace>
B.
研磨时没更换方向?xml:namespace prefix="o" ns="urn:schemas-microsoft-com:office:office">?xml:namespace>
C.
工件发热?xml:namespace prefix="o" ns="urn:schemas-microsoft-com:office:office">?xml:namespace>