A:but his works are not widely read
B:his works are not widely read
C:however, his works are not widely read
D:while his works are not widely read
小明今年a(a>5)岁,小红今年a﹣5岁,则7年以后,小明比小红大( )岁.
若 π4 是函数f(x)=sin2x+acos2x(a∈R且为常数)的零点,则f(x)的最大值是_____
在人类的性别决定中,决定后代性别的时期是( )