结构推理 Compare the thermal expansion of ceramics, metals and polymers using the symbol "＜" or "＞".
   For example: The hardness of ceramics is greater than metals. Thus, the comparison is expressed as ceramics ＞ metals. (2pts)
   Thermal expansion: A)
   From the above comparison, B) ______ have the lowest CTE and C) ______ have the weakest bonding forces among the aforementioned materials.