| investigate(verb, study, check, examine, request) |
| listen in(verb, expression, phrasal verb, study, consider) |
| look over(verb, expression, phrasal verb, study, consider) |
| penetrate(investigate, explore, research, delve) |
| pierce(investigate, explore, research, delve) |
| prod(investigate, explore, research, delve) |
| put out a feeler(expression, idiom, investigate, explore) |
| query(examine, request, investigate, ask, inspect) |
| review(verb, study, consider, examine, case) |
| scrutinize(study, consider, examine, question, investigate) |
| spy(verb, study, consider, examine, review) |
| study(consider, examine, request, question, investigate) |
| tap(verb, study, consider, examine, review) |
| test(investigate, explore, research, delve) |
| test the waters(expression, idiom, examine, investigate, inspect) |
| verify(investigate, explore, research, delve) |
| wiretap(verb, study, consider, examine, review) |
| quiz(investigate, explore, research, delve) |
| sounding out(verb, expression, approach, investigate) |