听下面一段较长对话，回答以下小题。
【小题1】What’s the conversation mainly about?

A．Fighting fire.

B．Detecting fire.

C．Preventing fire.

【小题2】What can we know from the conversation?

A．Australia lost 4% of its trees.

B．The system is used in America.

C．The system will use heat cameras.

【小题3】What size of fire can the new system discover?

A．The size of a car.

B．The size of a plane.

C．The size of a football field.

【小题4】What is the woman’s concern besides trees?

A．Protecting humans.

B．Purifying the air.

C．Saving animals.