— Mum, I will perform at the opening ceremony of the Youth Olympic.— ! We wish you a wonderful performance.
A:Thank you
B:The same to you
C:Congratulations
D:Never mind
饲养家蚕并观察其生殖发育过程,将其生殖发育不同阶段按时间顺序排列,正确的是( )
— .
已知a1,x,y,a2成等差数列, b1,x,y,b2成等比数列.则(a1+a2)2b1b2-2的取值范围是 ( )