19、The smell of gas on the street may make many of us hold our breath .However, when it comes to pollution, your own home may be just as bad.

"People spend most of their time indoors ,and their home can be two to five times（倍） as polluted as the air outside ," says the US Environmental Protection Agency.

Poor indoor air quality can cause health problems. And a lot of these problems are caused by what is in your house .To make your home healthy, here are some useful tips.

Is the fan in your bathroom working well? Turn it on. Put a sheet of paper against it. If the paper sticks ,the fan is strong enough .If not, it needs to be repaired .A good fan makes sure the air in the bathroom is fresh.

Keep your gutters（水槽） clean and clear so that dirty water doesn't make your kitchen or bathroom smell bad．

And don't leave the litter in bags or bins in your home .The place for it is outside,waiting for collection. When you are at home, open the windows to let fresh air in.

Follow these simple steps, and you're sure to live in a healthy environment,

（   ）1．According to the US Environmental Protection Agency, the air in your home may be _______ the air outside

A．more polluted than B．less polluted than      C．as bad as               D．no worse than

（   ）2．What does the underlined word “stick" mean in Chinese?

      A．坚持                      B．粘住                 C．破碎                    D．变湿

（   ）3．What is the sheet of paper mentioned in the passage used for?

      A．To clean the fan                        B．To make the air fresh

     C．To keep the fan new                      D．To tell you whether the tan is working well.

（   ）4．The passage mainly rolls us______

      A．how to buy a comfortable house         B．how the environment is polluted in cities

      C．how to make our home healthy          D．what a bad environment our house is