单选题 The number of computers in the library ______ twenty.
  • [A] is
  • [B] are
  • [C] have been
  • [D] be


【正确答案】 A
【答案解析】“the number of + 可数名词复数”结构后谓语动词应用单数。注意：a number of则表示“许多，很多”，谓语动问用复数。