血友病A患者缺乏（）
A.凝血因子Ⅲ
B.凝血因子Ⅷ
C.凝血因子Ⅸ
D.凝血因子Ⅹ
E.凝血因子Ⅻ
参考答案：B
As we know, ______ is good exercise and it is necessary for health.
[ ]
A. walk
B. to walk
C. walking
D. walked
隧道平面设计时，平面线形采用小半径曲线时将会出现哪些问题？
