German prepositions : interrogative pronoun referring to a THING

German prepositions : interrogative pronoun referring to a THING

When the interrogative pronoun, referring to a THING and NOT a person, is used with the 10 prepositions mentioned in the previous paragraph ( with the exceptions of " neben", and " zwischen"),

the usual form is " wo + prep" , instead of "prep + was".

2. Thus, we may have the following 10 prepositions : wobei, wodurch, wofür, wogegen, wohinter, womit, wonach, wovon, wovor and wozu.

3. if the preposition begins with a vowel, an " r" is inserted, giving : woran, worauf, woraus, worin, worüber, worum and worunter.

eg.

Mit wem bist du gekommen?

womit schreibst du?

4. When compounded with " wo-", wodurch, wonach, wovon and wozu do NOT generally express MOTION, for which purpose one would resort to "durch was", " woher", " wohin".

eg.,

Wodurch ist er so reich geworden?

Wonach fragt sie