Some words in English are shown in dictionaries as having three levels of stress: primary, secondary, unstressed or weak()
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____, on the whole, do not have much effect on the placement of the base or root element()
A. Suffixes
B. Affixes
C. Prefixes
Derivation
下列属于六个基本视图的有()
A. 俯视图
B. 右视图
C. 后视图
D. 斜视图
压缩机,离心机,鼓风机,反应罐和搅拌装置等统称为化工机器()