从右栏选项中找出左栏各句的恰当应答。

                I                                                                                                   II

46. 1.Hello,Jenny speaking. ____                                             A.I like music that I can dance to.
47. 2.How often does Jeff go to the library? ____                   B. It's 876-9548.
    
48. 3.What's your telephone number?    ____                         C. They're pretty good.
    
49. 4.What do you think of the cartoons? ____                       D. Hi, Jenny. It's Steve.
    
50. 5.What kind of music do you like?  ____                            E. Hi, I'm Jack.
    

                                                                                                   F. Once a week.

“种姓制度”实行于（   ）

如图为人体新陈代谢的过程示意图．

如图所示，ABCD是一直角梯形棱镜的横截面，位于截面所在平面内的一束光线由O点垂直AD边射入，已知棱镜的折射率n= $\sqrt{2}$ ，AB=BC=8cm，OA=3cm，∠OAB=60°．