单选题 Plastic bags are useful for holding many kinds of food, ______ their cleanness, toughness and low cost.
  • A. by virtue of
  • B. in addition to
  • C. for the sake of
  • D. as opposed to
【正确答案】 A
【答案解析】[解析] 各选项的意思为：by virtue of依靠，由于。in addition to除……之外。for the sake of为了。as opposed to与……相反，与……相对比。答案是A。