氟骨病和氟斑牙主要是由于（）的原因造成的。
A.膳食中长期氟摄入不足
B.钙和磷的摄入不足
C.高氟地区居民长期摄入含氟高的饮水
D.尚未发现
参考答案：C
_____ since the night before, I felt very hungry. [ ]
A. Having not eaten anything
B. Not eating anything
C. I hadn't eaten anything
D. Not having eaten anything
血型亚型
