为了防止聚合物溶液降解，整套聚合物分散装臵全部采用（）材料。
A、不锈钢
B、聚乙烯
C、铝合金
D、橡胶
参考答案：A
椎间盘应是
A．有血液供应的纤维软骨板
B．为一纤维板
C．由纤维环、软骨板、髓核构成
D．含有大量水分和粘多糖的物质
E．为一软骨板
Great changes _____ in the village in the past few years. [ ]
A. took place
B. take place
C. will take place
D. have taken place
