A:最小值为
B:最小值为
C:最大值为
D:最大值为
某班有50名同学,在一次测验中答对第一题的有25人,答对第二题的有20人,两题都答对的有10人,则有几名同学两题都不对?
— I think travelling by train is more comfortable than travelling by plane.—_________. In my opinion, travelling by plane is more comfortable.
一对正常夫妇生了“龙凤双胞胎”,其中男孩色盲,女孩正常。则此夫妇的基因型为()