A．Some birds can only use the sun to guide them.
B．Some birds can only use the stars to guide them.
C．When it is too dark to see anything, birds still can find their direction.
D．Any change in the position of the make-believe stars would cause a change in the direction of the birds flights.

A．He spends too much money.
B．He bought an expensive watch.
C．He really does like TV
D．He should watch more TV