A、Shoes can leave scratches on the floor. B、The marks left by shoes are hard to erase. C、Shoes can upset family members with the

While it has long been a practice in Asian countries, many people in Western countries have yet to embrace that no shoes in the house rule. For many in those countries wiping their shoes before going inside is recorded as sufficient. After all, they may think a little dirt doesn’t hurt anyone, but I can give you several good reasons why people should remove their shoes before going inside their homes.
    Bacteria are everywhere. They collect on your shoes when you walk along sidewalks, public-toilet floors and even office carpets. In one study conducted at an American university, researchers collected microscopic germs from footwear. They found that up to 421,000 units of bacteria can collect on the outside of a single shoe, and it only takes a little bit of dirt to damage your timber floors. The more dirt you track in, the more it scratches and the more often you have to clean. The extra scrubbing will harm your floors over time. Shoes can also leave marks and scratches on floors, especially high heels or shoes with pointy or hard parts. These can dent and scratch your floor. And if you live in an apartment building, removing your noisy shoes is the polite thing to do out of consideration for your downstairs neighbors. Walking around with bare feet is actually better for your feet. It strengthens the muscles in your feet. So many people are accustomed to wearing shoes during all their waking hours. The more time you spend wearing shoes, the more likely you are to incur foot injuries as a result.
    And if people aren’t yet convinced by my arguments, I can give one final reason. The dust and toxic chemicals you bring into your house via your shoes can deteriorate the air quality in your home. Toxic chemicals are everywhere in our lives—insect killing chemicals used on public grass areas, cleaning chemicals on the floors of public areas. By kicking off your shoes before you enter the home, you are denying entry to these harmful chemicals. Given the amount of time we spend in classrooms and the number of shoes that pass through them every day, you may well understand me if I were to propose a NO SHOES in the classroom rule.
    16.Why don’t many westerners take off shoes before entering a house?
    17.What is the finding of one study by researchers at an American university?
    18.What is the final reason the speaker gives for removing shoes before entering a house?