单项选择题
There are at least a dozen inflectional affixes. ( )
单项选择题 精清中的蛋白质含量很低,一般为( ) A. 1%-2% B. 2%-5% C. 3%-7% D. 7%-10%
多项选择题 What are the principles that a concierge should follow? A、Serve guests heart and soul. B、Be friendly to guests. C、Be passionate to guests. D、Neglect the guest's demand.
不定项选择 即使短期边际产品递减，长期的边际产品仍然有可能递增。（最好在纸上写一个具体的函数来判断）
