单选题 These instruments are so powerful as to enable them to {{U}}ascertain{{/U}} many facts of the deepest interest.
  • A. put out
  • B. find out
  • C. wear out
  • D. turn out
【正确答案】 B
【答案解析】ascertain：查明；put out：扑灭，伸出；find out：了解，搞清楚，查明(经常接疑问词引导的从句，多数情况下不能与find替换。其意义并非强调结果)；wear out：使……筋疲力尽，穿坏；turn out：后来发现是……，被证明是……