相对于其他育种方式，诱变育种特有的优点是[ ]
A．方法简单易行
B．能产生很多有利的个体
C．节省实验材料
D．提高变异频率，加速育种进程
答案：D
Li Na plays ________ tennis very well. She has become ________ first Asian woman
to reach a Grand Slam (大满贯) final. [ ]
A. a, the
B. /, the
C. the, a
D. /, a
运行中显示“主接地”灯亮，主断分闸时应如何处理？
