哪些是引起慢性肺心痛肺动脉高压的因素
A.儿茶酚胺分泌增多
B.水、钠潴留使血容量增多
C.肺泡毛细血管床减少
D.红细胞增多
E.肺血管重塑
参考答案:A,B,C,D,E
Amy ____ the school library. She ______ books three times a week.
A.has gone to; has used to borrow
B.has been to; used to borrow
C.has gone to; has been used to borrowing
D.has been to; is used to borrowing
定性研究方法常用于()。
A.推断事物的总体特征
B.研究事物的结果
C.快速评估
D.检验问卷的信度与效度
E.样本量较大时