【题目】They are________ different sizes, shapes and metals, but they are exactly the same________.
A.不填;in weights
B.of; in weight
C.in; of weight
D.of; weights

【答案】B
【解析】第一空of different sizes，shapes and metals为of + 名词结构；第二空in weight表示“在重量上”；句意：虽然它们尺寸、形状和金属不同，但它们在重量上完全一样。根据句意，故选B。