单选题
Researchers say infants who are exposed to things like rat and pet dander (屑), roach (蟑螂) allergens (过敏原) and household bacteria during their first year are actually less likely to suffer from allergies. A new study published in the Journal of Allergy and Clinical Immunology shows that being exposed to allergens before a child turns one can 27 allergies. To reach these findings, the researchers studied 467 inner-city infants in Boston and New York. They tracked their health over three years, and visited their homes to calculate the levels of a 28 of allergens. They also conducted allergy tests on the children and collected bacteria from dust 29 in their homes. The kids who lived homes with mouse and cat dander as well as cockroach droppings during their first year had lower rates of wheezing (喘息) by age 3. It's possible you've heard of the 'hygiene hypothesis', which is the 30 that the reason Americans have so many allergies is because we are, quite simply, too clean. Kids are kept in such completely clean environments that they never 31 immunities to common allergens. A significant amount of research has shown that kids who grow up living on farms with livestock, or with a pet are less likely to 32 allergies: Prior research has also suggested that it's not 33 dust that provides protection, but the microbes (微生物) that are in our body that influence our immune system and ability to fight off 34 . The new findings support a growing body of 35 that a little exposure to germs here and there never hurt no one, and in fact, could actually be protective. Letting a child put their shoe in their mouth is 36 , but possibly not the worst accident they could make. A. benefit I. gross B. build J. infections C. develop K. lawfully D. domination L. marvelous E. endangered M. necessarily F. evidence N. speculation G. gathered O. variety H. granted