视神经萎缩症是一种显性遗传病,若一对夫妇均为杂合子,生正常孩子的概率为:
A:25%
B:12.5%
C:75%
D:45%
某同学通过实验发现,同样条件下α-淀粉酶在35 ℃时催化效率不如唾液淀粉酶高。该同学想就这一问题做进一步探究实验,下列哪一项探究课题最合理( )
Last year, three hundred English teachers took part in the ______ English training.