Swifts（雨燕） live mostly in the air.These small birds are among the fastest animals on Earth.In fact,swifts can go two or three days without touching the ground!To get used to life in the sky,swifts use their speed and the saliva（唾液）in their mouths.
Swifts can fly faster than 100 miles per hour.That\’s because their wings are like boomerangs （飞行器）.This shape of the wings helps them to fly much faster.They can also move one wing faster than the other,which allows them to make sharp turns without slowing down.Making fast,sharp turns helps swifts catching flying bugs to eat.
The saliva helps swifts catch bugs to feed their young. It is sticky,like glue.Swifts often fly into clouds of bugs such as mosquitoes and open their wide mouths to catch as many insects as they can.The bird collects insects in its mouth gradually and holds the insects in a sticky ball of saliva.One food ball can contain nearly 1,000 bugs.
Swifts also use their saliva as glue to build their nests.The birds catch feathers in the air and stick the feathers together to build a strong nest on the side of a building.Swifts\’ short feet are not good for walking or standing on land for long.But their sharp claws allow them to stick to rocks and walls so they can take a brief rest before returning their lives in the sky.

（1）The second paragraph mainly talks about ______.
A．how fast swifts can fly
B．how swifts turn around in the sky
C．why swifts make sharp turns
D．why swifts can fly and turn so fast
（2）What does the underlined word "it" refer to in paragraph 3? ______
A．the saliva
B．the swifts
C．the bugs
D．the glue
（3）Which of the following is TRUE about swifts? ______
A．Swifts don\’t usually live on land because of their wings.
B．Swifts can fly for a long time because of their small bodies.
C．Swifts can\’t walk for a long time because of their short feet.
D．Swifts can catch nearly 1,000 bugs at the same time with the saliva.
（4）Which of the following is the best title for the passage? ______
A．Life in the Sky
B．A Small Pet
C．The Fastest Speed
D．The Special Saliva