玉米F1的100个孢母细胞中，交换发生在Cc和Shsh相连区段之内的有7个，则这两对基因间的重组率为（）
参考答案：3.5%
动脉导管未闭可听到
A．Graham-Steel杂音
B．Austin-Flint杂音
C．胸骨左缘3～4肋间收缩期喷射性杂音
D．心尖区收缩中期喀喇音
E．胸骨左缘2肋间Gibson杂音
—I don't know _______.
—You can go and ask Jack. [ ]
A. when does the train leave
B. that we will plant trees or not
C. if she had come yesterday
D. what I should buy for him
