脚手架长度是指脚手架纵向两端立杆（）间的水平距离。
A.轴线
B.外皮
C.垂直轴线
参考答案：B
初产妇，产后第2日开始发热，体温38℃左右，已持续10小时。子宫收缩好，无压痛，会阴切口无红肿疼痛，恶露正常无异味， * * 肿胀有硬结。发热原因可能是（）
A.乳腺管不通
B.泌乳热
C.上呼吸道感染
D.产褥感染
E.乳腺炎
For a group of n people, k of whom are of the same sex, the expression yields an index for a certain phenomenon in group dynamics for members of that sex. For a group that, consists of 20 people, 4 of whom are females, by how much does the index for the females exceed the index for the males in the group ？（）
yields an index for a certain phenomenon in group dynamics for members of that sex. For a group that, consists of 20 people, 4 of whom are females, by how much does the index for the females exceed the index for the males in the group ？（）