分娩前没有乳汁分泌是因为血中雌激素和孕激素浓度过高。()
参考答案：对
Kitty said that she had grown crazy about nature because she hadn't been ____ too long. [ ]
A. outdoors
B. indoor
C. indoors
D. outdoor
疱疹性龈口炎多见于
A．6个月～3岁婴幼儿
B．学龄前儿童
C．青少年
D．中年人
E．老年人
