哺乳仔猪对温度的最适温度为()
A. 25—30℃
B. 20—23℃
C. 15—18℃
D. 20—23℃
邮件的生产传递过程大致可分为收寄、()、运输和投递4个基本环节。
A. 分拣封发
B. 交接
C. 中转
D. 派班
The purpose of the ashing step in graphite-furnace atomic-absorption spec-troscopy is to()
A. Vaporize metal atoms to be analyzed
B. Cause the metal species to form carbides which are more volatile
Convert the graphite furnace to ash to avoid carbide formation
D. Burn off organic species that would interfere with the elemental analysis
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