某学龄前儿童指甲凹陷，该儿童患的是（），对他最有效的食物是排骨或瘦肉。
参考答案：缺铁性贫血病
Five _______ students from different schools took part in the English contest last Saturday. [ ]
A. hundred of
B. hundred
C. hundreds of
D. hundreds
小儿上呼吸道感染常见夹滞的原因是( )
A．肺常不足B．脾常不足C．肝常有余D．肾常虚E．肺脏娇嫩
