When a conditional begins with inverted “Had,” rewrite it as an “if ... had” clause and place the consequence on the timeline. Then determine voice independently: identify whether the result-clause subject performs or receives the action before combining the required tense, modality, and voice.
Hints
- Hint 1
Rewrite the opening
Mentally convert the inverted opening into an equivalent condition beginning with “If.”
- Hint 2
Establish the timeline
Determine whether both the imagined result and the actual replication belong to the future, the present, or the completed past.
- Hint 3
Track the action
Use the phrase beginning with “by” to determine whether the clause’s subject performs the recording or receives it.
Step-by-step
- Step 1
Undo the inversion
“Had the elevated radium readings reflected ...” is equivalent to “If the elevated radium readings had reflected ....” The condition is past perfect and contrary to fact.
- Step 2
Place the result in time
The result clause refers to the explicitly dated 1932 replication, and the clause after the semicolon reports the actual recording in the simple past. The imagined result is therefore an unreal alternative to a completed past event.
- Step 3
Determine the voice
The subject of the result clause is “the same numerical values,” but the equipment performs the recording. The phrase beginning with “by” therefore requires a passive verb construction.
- Step 4
Match the conditional form
An unreal past condition pairs with a modal-perfect result. Combining that form with the required passive voice yields “would not have been recorded.”