题目内容：

 

    The sun is setting on a summer night. At the entrance to a deep dark cave, a few bats fly out high up into the air. More and more of the small creatures appear. Within a few minutes, a whole river of bats is pouring out of the cave, and they keep coming, millions and millions of them.

Sounds like a scary horror movie? Believe it or not, this scene takes place every night,all summer long,at Bracken Cave in Texas, where 20 million bats fly outside to feed on insects. Every March or April, Mexican free-tailed bats fly up to 1,000 miles from their winter home in Mexico to this cave, where they raise their young. Soon after they arrive, each mother gives birth to a baby. As many as 500 baby bats crowd into one square foot of space. All those badies create nice warm temperatures to keep them comfortable. If you’ve ever lost sight of your parents on a crowded playground, you may be wondering how mother bats recognize their babies. They use their sense of smell to recognize their own babies when it is time for the babies to nurse.

The cave, a quiet place in winter, filled with life all summer. Bat poop, called guano, soon covers the floor,prviding food for tiny organisms(微生物). And then come the bugs. Kennedy says, “you walk in with your headlight on and the floor of the cave is full of bugs. Insects are flying around, and bectles(甲虫) move slowly up you legs!”

    When the adult bats leave the cave at night of feed, they are helping humans.They eat tons of insects in a single night, including many pests that eat farmer’s crops. And they get rid of mosquitoes, too. When twenty million bats fly out of one cave opening, they make a column so thick that they show up on radar at the nearby airport. It can take three hours for all of them be to come out.

1.Mexican free-taled bats fly to Texax every March or April because          ．   

  A．they can find lots of food    B．the cave is bigger

  C．they give birth to baby bats  D．they can protect the crops

2.The mother bat finds its baby by          ．

  A．smelling    B．hearing    C．touching    D．watching

3.The underlined word “poop” probably means          ．

  A．body     B．waste    C．food    D．cave

4.Whhich of the following is right?   

  A．As many as 500 baby bats crowd into one cave.

  B．It’s easy for all the bats to get out of the cave quickly.

  C．A mother bat will bear at least one babyb at at a time.

D．Bats eat many crop pests and mosquitoes.