根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。
Indoor air pollution belongs to one of the top five environmental health risks. It is a fact that air pollutants in your home may be containing harmful particles(颗粒) for our health. It is a wise way to control it.  
What are the pollutants that come in indoor air pollution?
  Those particulate matters include dust, smoke and other particles which are generated from the combustion(燃烧)appliances such as cooking stoves. It can also contain tiny organism such as viruses, bacteria, dust mites.
___  Building material can also bring pollutants such as paints, cleaning products, pesticides(杀虫剂) and so on. How to deal with indoor air pollution?
There are some ways you can do to deal with your indoor air pollution.   However, if the contaminants come to the outdoor environment, you have to find an alternative. This cleaning device(装置)can be a good option for your problem.
Air cleaning device is designed to be able to remove virtually all the pollutants contained in the indoor environment. There are basically two types of air cleaning device, whole house air and portable air cleaning device. Portable air cleaner is ideal for small room or specific area.      

A．Generally, indoor air pollution contains pollutants, such as particulate matters and gaseous pollutants.

B．However, it is better to know the harmful particles that come in the air in your home.

C．The gaseous pollutants are mostly generated from the process of combustion including vehicle exhaust, gas cooking stoves, and also tobacco smoke.

D．The first thing you can do is to give ventilation(通风) for your home with clean outdoor air.

E. Indoor air pollution contains many harmful chemical matters.
F. Meanwhile, whole house air cleaner can cover larger area in your home.
G. On the contrary, large air cleaner can get rid of all the pollutants.