A．Not to subscribe to the journal.
B．To buy the latest issue of the magazine.
C．To find a better science journal in the library.
D．Not to miss any chance to collect useful information.

A．To show the key role played by air traffic controllers.
B．To show the great responsibility shouldered by the pilots.
C．To give an example of air disasters.
D．To show that air travel is far safer than driving a car.