Questions 15～18 are based on the following dialogue. How much does the book of nineteenth-century plays cost

A．It was getting dark.
B．He was afraid of being blamed by his friend.
C．The birds might have flown away.
D．His friend would arrive any time.

A．He drives too fast.
B．He plays his guitar too loudly,
C．His radio wakes the children.
D．His friends are too noisy.