Questions 15～18 are based on the following passage.

When did the city get the name San Francisco

A．The library no longer had the book on reserve.
B．The library closed earlier than he’d expected.
C．The professor had chosen a mystery book for him instead.
D．The homework assignment isn’t clear.

A．elderly American people are neglected by their children
B．elderly American people suffer from loneliness
C．elderly American people can’t enjoy family happiness
D．elderly American people can enjoy family happiness