Steven Stein likes to track garbage trucks．He says，"It's hard to resist．"Stein's strange habit makes sense when you consider that he's an environmental scientist who studies how to reduce litter，including stuff that falls off garbage trucks as they run down the road．What is even more interesting is that one of Stein's current plans is defending an industry behind a source of trash：plastic shopping bags．Americans use more than 100million plastic bags every year．So many end up in tree branches or along highways that a growing number of cities are banishing(排除)them from checkout lines．The bags are outlawed in some places in the USA．Facing these situations，plastic-bag manufacturers are hiring scientists like Stein to make the case that their products are not as bad for the planet as most people assume．"It's important to base your decisions on facts，"says Stan Bikulege，CEO of Hilex Poly，which has hired Stein．Among the bag makers'argument：many cities with bans still allow shoppers to purchase paper bags，which are easily recycled but require more energy to produce and transport．And while plastic bags may be ugly to look at，they represent a small percentage of all garbage on the ground today．The industry has also taken aim at the product that can take the place of plastic bags：reusable shopping bags．The sturdier a reusable bag is，the longer its life and the more plastic-bag use it cancels out．But this plan has another side．Longer-lasting reusable bags often require more energy to make．Environmentalists don't agree with these points．They hope paper bags will be banned someday too and want shoppers to use the same reusable bags for years．So are reusables our destiny(命运)？the answer is probably yes．And Andy Keller，inventor of reusable polyester(聚酯纤维)bags，says，"If you can carry it out in your hands or put it back in your car，you don't need a bag．"32．For what purpose are scientists like Stein hired by plastic-bag makers？___A．To collect facts about shopping bags．B．To show plastic bags are eco-friendly．C．To research on people's consuming habits．D．To prove plastic bags are better than people thought．33．Which disadvantage of paper bags is mentioned by plastic-bag makers？___A．They look a bit ugly．B．They are easy to break．C．Their prices are comparatively high．D．Their production is energy-consuming．34．What does the underlined word"sturdier"in Paragraph 5probably mean？___A．Stronger．B．Lighter．C．Heavier．D．Softer．35．What's the best title for the text？___A．Forget about plastic bagsB．Paper bags are comingC．Paper，plastic or neitherD．A strange scientist．