Rule details
B2 (Upper-Intermediate)
Conditional inversion (without if):
Had + subject + V3, ...
Should + subject + V, ...
Were + subject + to + V, ...
Emphatic inversion:
Never / Rarely / Seldom / Not only ... + auxiliary + subject + verb
Example: Had I known, I would have acted differently.
Conditional inversion (third conditional):
Had I known about the problem, I would have helped you.
Conditional inversion (first conditional):
Should you need assistance, call me immediately.
Emphatic inversion:
Never have I seen such a beautiful sunset.
Emphatic inversion with Not only ... but also:
Not only did he win the race, but he also broke the record.
Conditional inversion vs normal conditional
It removes if and gives the sentence a more formal style.
Emphatic inversion
Used to strengthen the statement and make speech more expressive.