过原点的抛物线的解析式是（　　）

A．y=3x²-1

B．y=3x²+1

C．y=3（x+1）²

D．y=3x²+x

David was born _____1994, and his birthday is _____ April 23rd.[ ]

A. in, on  

B. at, in  

C. on,on  

D. in, in