Perhaps you should try some spelling variations:
decreased teaching » decreased reactive (Expand search)
teaching object » teaching subject (Expand search), teaching project (Expand search), learning object (Expand search)
by decreased » is decreased (Expand search), _ decreased (Expand search), to decreased (Expand search)
decrease at » decrease akt (Expand search), decrease and (Expand search), decrease in (Expand search)
at decrease » rate decrease (Expand search), that decrease (Expand search), and decrease (Expand search)
decrease of » decrease in (Expand search)
of decrease » or decrease (Expand search), not decrease (Expand search), to decrease (Expand search)
decrease by » decreased by (Expand search), decrease in (Expand search), decrease _ (Expand search)

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease at decrease of decrease ) OR ( decrease by decreased teaching object ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease at decrease of decrease ) OR ( decrease by decreased teaching object ))*.