Adjective clause with preposition



Why, in some sentences, must we add a preposition before the "which" clause and why in some sentences must we not add a preposition before the "which" clause?

And can you tell me some example sentences of "of which," "for which," "at which," "in which"? Can you give a detailed explation?

Why don't the grammar books give much detail on it? Which grammar books have talk about it?

Jeff Wong
Posted 19 December 2001
Betty Azar's Understanding and Using English Grammar, 3rd ed. (Pearson Education, 1999), explains very clearly how to use adjective clauses with prepositions. Click here to see the chart and explanation from page 269 of that grammar book.