在高等动物中，脊索和背神经管分别演化为（ ）
A. 脊柱和脊髓
B. 脊髓和脊柱
C. 脊髓
D. 脊柱和骨髓
下列属于原索动物的有：（ ）
A. 文昌鱼
B. 河蚌
C. 海鞘
D. 海参
[音频]Listen to the dialogue again, and then choose the best answer.1. Where does the conversation take place?
At the woman’s home.
B. At the man’s home.
C. On campus.
2. The two speakers _______.
A. haven’t met each other for a long time
B. met each other only yesterday
C. met each other last year
微信支付 
支付宝支付