According to the news, US President Barack Obama made a solemn trip to Delaware Tuesday, to honor the troops killed in a helicopter crash in______.

A．separate schools for deaf and hard-of-hearing children
B．separate schools for blind children
C．schools in which students are encouraged to sign
D．schools in which listening and spoken language approach is used

A．The South Atlantic.
B．The North Atlantic.
C．The North Pacific.
D．The South Pacifi