B
Swifts (雨燕) live mostly in the air. Their short feet are not good for walking or standing on land for long. To get used to life in the sky, swifts use their speed and the saliva (唾液).
Swifts can fly faster than 100 miles per hour. That's because their wings are like boomerangs (回力镖). This shape of the wings helps them to fly fast. Swifts can also move one wing faster than the other. It allows them to make sharp turns without slowing down. Making fast and sharp turns helps swifts catch flying insects to eat in the sky.
The saliva helps swifts catch insects to feed their young. It is sticky, like glue. Swifts often fly into clouds of insects and open their mouth wide to catch as many insects as they can. They collect insects in their mouth gradually (逐渐地) and hold the insects in a sticky ball of saliva. One ball like this can contain nearly 1,000 insects. 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.
() 31. What does Paragraph 2 mainly talk about?
A. Why swifts' wings are like boomerangs. B. How swifts catch insects in the sky. C. How swifts make sharp turns in the sky. D. How swifts fly and turn fast in the sky.
() 32. What does the underlined word "It" refer to in Paragraph 3?
A. The saliva. B. The air. C. The shape. D. The speed.
() 33. Which of the following is true about swifts?
A. They don't usually live on land because of wings. B. They can fly for a long time because of their small bodies. C. They can't walk for a long time because of their short feet. D. They can catch nearly 1,000 insects in one go with the saliva.
() 34. What is the use of the swifts' saliva?
A. It helps the swifts walk on land for long. B. It is used to help build strong nests. C. It helps the swifts fly faster in the open air. D. It is used to help keep the insects away.
() 35. Which of the following is the best title for the passage?
A. The sky-living master B. The amazing small pet C. The fastest speed D. The special saliva