---Mum, could you buy me a dress like this?  

--Certainly, we can buy _______ one than this, but ________ this.

A．a better; better than

B．a worse; as good as

C．a cheaper; as good as

D．a more important; not as good as

激活NK细胞，增强细胞免疫功能的细胞因子是（）

A.IL-2、IL-4

B.IL-5、IL-7

C.IL-12、IFN-γ

D.IL-8、IL-12、GM-CSF

E.IL-1、IL-3