Perhaps you should try some spelling variations:
decrease their » decrease the (Expand search), increase their (Expand search), decreases the (Expand search)
decrease rate » decreased rate (Expand search), decreases rate (Expand search), decrease at (Expand search)
rate decrease » rats decreases (Expand search), rate increase (Expand search), to decrease (Expand search)
their mastery » the mastery (Expand search), their masses (Expand search), their markers (Expand search)
decrease any » decrease and (Expand search), decreases and (Expand search), decreased and (Expand search)
any decrease » and decrease (Expand search), can decrease (Expand search), may 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 rate decrease OR decrease ) OR ( decrease any decrease their mastery ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease rate decrease OR decrease ) OR ( decrease any decrease their mastery ))*.