請求信：…This decision was not taken lightly,and I do appreciate the king consideration you have shown to me .空氣污染 ……Actually,people are showing a rel concern over the problem.For example, there is an increasingly loud voice from the public for firm action against pollution from automobiles.順便問下，在背誦過程中，我老是記不清何時用for或from 、of等，請問老師如何才能準確得記住它們，謝謝！