Hello,<br/>According to Macmillian dictionary,<br/><br/><b>element in: </b><br/><a href='http://www.macmillandictionary.com/search/british/direct/?q=advertising' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=advertising</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=is' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=is</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=not' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=not</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=only' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=only</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=element' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=element</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=in' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=in</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=marketing' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=marketing</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=process' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=process</a>.<br/><br/><b>element of: </b><br/><a href='http://www.macmillandictionary.com/search/british/direct/?q=fieldwork' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=fieldwork</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=a' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=a</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=key' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=key</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=this' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=this</a> <a href='http://www.macmillandictionary.com/search/british/direct/?q=course' target='_blank' rel='nofollow'>http://www.macmillandictionary.com/search/british/direct/?q=course</a>.<br/><br/>When do you use IN and OF? Or it is ok to use whatever you feel like using for anything?<br/>Thanks.