单选题 It was five o'clock in the afternoon ______ they climbed up to the top of the mountain.
  • A.since
  • B.when
  • C.that
  • D.until
【正确答案】 B
【答案解析】[解析] when引导时间状语从句，若主语的表语为at five o'clock in the afternoon，则用强调句型的引导词that。