As it was his first time to visit the science museum, the boy seemed ___about everything there.     [ ]

A. anxious      

B. curious    

C. particular    

D. frightened

一般来说，比例税率的形式主要包括( )。

A．协议比例税率

B．幅度比例税率

C．差别比例税率

D．固定比例税率

E．单一比例税率