我国绝大部分领土位于（ ）
A．热带
B．北温带
C．南温带
D．寒带
我国绝大部分领土位于北温带，小部分位于热带，没有寒带．
故选：B．
X-连锁淋巴组织增生性疾病对以下哪种病原体易感
A．C杆菌
B．呼吸道合胞病毒
C．EB病毒
D．巨细胞病毒
E．单纯疱疹病毒
Which of the following statements regarding marginal costs (MC) and average variable costs (AVC) is most accurate（）
A. MC = AVC when AVC is at its minimum.
B. MC ＜ AVC when AVC is at its minimum.
C. MC = Average total cost when AVC is at its minimum.
