› to discover something:
[ + question word ] Have you ascertained whether she's coming or not?
› to make certain of something:
[ + that ] I ascertained that no one could overhear us before I told Otto the news.
词库：同义词和关联词
- a fishing expedition idiom
- alight
- break fresh/new ground idiom
- breakthrough
- catch sb red-handed idiom
- catch sb with their pants/trousers down idiom
- flush
- happen
- happen on/upon sth/sb
- have a (good) nose for sth idiom
- have got something there idiom
- hidden
- run sb/sth to ground idiom
- search
- search sth/sb out
- smell
- sniff sth out
- sniff sth/sb out
- stumble
- trace
