On April 13th, 2012____ press conference is held by Los Angeles Police Department at_____crime

scene of a shooting incident. [ ]

A. a; the          

B. a; a          

C. the; a          

D. the; the

-How do you know that she likes singing?

-I often hear her      after class.

A．to sing

B．singing

C．sing

D．sings