【单选题】Which is the structure of the following argument? “Joe is not a prison guard, since he is a former felon, and former felons are not allowed to become prison guards”
D.
a combination of more than one of these structures
【单选题】有关社会学发展的两个方向,以下说法中正确的是
D.
一是走向与人类学的融合,二是走向与人类学的分离
【单选题】Joe likes to sleep late in the mornings and play tennis in the afternoons. The opportunity cost of Joe attending his morning class for one hour is
A.
an hour of tennis given up.
B.
an hour of sleep given up.
C.
both the tennis given up and the sleep given up.
D.
nothing because he is paying for his class.
【单选题】下面说法正确的是( )
C.
若 不存在,则曲线 在点 处的切线斜率不存在
【简答题】曲线 在点 处切线斜率存在是 在点 处可导的____条件。