简述体育习惯的特点
参考答案：
（1）后天性
（2）稳固性
（3）指向性
（4）省力性
__________ after a whole day’s work that he could hardly stand it.
A．So he was tired and hungry
B．Was he so tired and hungry
C．So tired and hungry was he
D．So tired and hungry he was
用原子吸收分光光度法测定高纯Zn中的Fe含量时，采用优级纯的HCl作为分解样品的试剂。( )
