[nonohoney]

thanks dear
i got it now , look in page 35 paragraph D
i wrote the topic outdoor pollution
the main idea what causes sick buliding syndrome in an officebuilding or i think this sentence is more spacific
experts have discoverd several sources of sick building syndrome
as i read in stratege that the main idea can be in the first sentence or second one and its also, answer for what the writer want to said about the topic