The pill is, after sterilization, the most frequent form of birth control in this country.
A frequent form of execution by these groups is decapitation, another is shooting.
An even less frequent form is ozone, although chlorine often is added in this process.
Votive offerings are the most frequent form of offering.
The most frequent form of resistance was flight, which often led to death.
The most frequent (and dangerous) form of levee failure is a breach.
I suppose caning was a a more frequent form of discipline, in those days?
A frequent form is the internal mold of brachiopods.
Beta-propellers are a quite frequent form of adaptable surface for interaction between different proteins.
The most frequent form is genital beading, using small, round implants.