Questions 11 to 18 are based on the conversation you have just heard.

A．Names of the operators.
B．People’s names, addresses, and telephone numbers.
C．All businesses, hotels, restaurants, shops, etc.
D．Phone fee.

A．Heavy, green water which changes salt dust to high grade petroleum.
B．Heavy, green dust which changes salt water to high grade petroleum.
C．Light, grey water which changes salt dust to high grade petroleum.
D．Light, grey dust which changes salt dust to high grade petroleum.