在整个呼吸周期中正常吸气占1/3。
参考答案：对
_______ from father to son, the music has not changed for centuries.
A．Passing
B．To pass
C．Having passed
D．Passed
生物各类群之间所处的共同分类单位越小，其相似的形态结构特征越多．______．
