加入后能够有效提高塑料弹性、可塑性、流动性,改善塑料低温脆化的助剂是()。
A. 填充剂
B. 增塑剂
C. 稳定剂
D. 润滑剂
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You work as a database administrator for Certkiller .com. As a result of performance analysis, you created an index on theprod_namecolumn of the Certkiller prodtable, which contains about ten thousand rows. Later, you updated a product name in the table. How does this change affect the index?()
A leaf will be marked as invalid.
B. An update in a leaf row takes place.
C. The index will be updated automatically at commit.
D. A leaf row in the index will be deleted and inserted.
E. The index becomes invalid when you make any update
下列哪些物品属于内河船舶垃圾()
A. 在船舶营运中产生并需随时或定期处理的食品
B. 在船舶营运中产生并需随时或定期处理的生活废弃物
C. 粪便
D. 机舱舱底水