Which preposition to use with preparatory

to Occurrences 286%

The digging of the soil preparatory to raising a corn-crop is work; the making of brooms; the writing of fugues.

for Occurrences 8%

Preparatory for that day, it is Britain's duty to compel Germany's respect.

in Occurrences 2%

Students of the preparatory year of law, of the fifth of the secondary course, of the preparatory in medicine, formed lively groups.

Which preposition to use with  preparatory