单选题 (All) fruit contains fiber: an orange provides seven, (a apple five), and a banana four, but (half of) a grapefruit (provides) six grams.
  • A. All
  • B. a apple five
  • C. half of
  • D. provides


【正确答案】 B
【答案解析】以元音开头的可数名词，不定冠词要使用an，比如an apple，an hour，an elephant等。