Plants are more than just pretty to look at.They give us fruits，vegetables and food we eat.Some plants even provide materials for medicine or building things.But do you know that plants can do something even more amazing？They can make our homes，schools and workplaces much healthier.
    We spend a large part of our day indoors.Unluckily，the air inside buildings can often be full of chemicals（化學(xué)物質(zhì)） from many things around us.This poor air quality（質(zhì)量） can make us feel sick，causing sore eyes and throats，and even making it hard for us to breathe.When the air inside buildings gets really bad，people even call them "sick buildings".
    The good news is that plants are like nature's little superheroes.They have a magic power fighting against bad air.Plants breathe in carbon dioxide（CO₂） and breathe out oxygen（O₂） which we humans need to live.They can also add moisture to the air if it's too dry，making it more comfortable for us to breathe.
    ______Scientists have discovered that plants have the ability to take in harmful chemicals，making the air around us safer to breathe.They set up a completely closed building called "bio-home"for experiments.Before they added plants，the air inside was full of chemicals and people found it hard to breathe.But after they added plants，the air got much cleaner and it became easier to breathe.To make the air inside even better，the scientists used different kinds of plants.After a while，the building wasn't a "sick building"any more.People could go inside without feeling unwell.
    So you see，plants are fantastic!They are not only beautiful to look at，but they also provide us with food，help create materials and play an important role in our health.They make our indoor environments cleaner and healthier，making us feel better.Next time you see a plant，remember all the amazing things it can do for us!

（1）Which of the following is one way for plants to improve the air inside buildings？

B

B

A．They breathe out carbon dioxide.
B．They produce oxygen.
C．They give out harmful chemicals.
D．They make the air dry.
（2）Which can be the best to fill in the blank

A

A

in Paragraph 4？
A．But the most amazing thing plants can do is to clean the air.
B．But one interesting thing plants can do is to build things.
C．But plants can provide what humans need to eat.
D．But plants can be used to make medicine for humans.
（3）How does the writer support his opinion about plants improving air quality？

D

D

A．By telling personal experiences.
B．By providing numbers and forms.
C．By questioning famous scientists.
D．By using scientific experiments.
（4）What does the writer mainly want to tell us？

C

C

A．Plants are important for providing food.
B．Plants make people look much better.
C．Plants are good for indoor environments.
D．Plants make it easier to build houses.