Perhaps you should try some spelling variations:
primary animal » primates animal, primary aims, primary avian
primary tool » primary tools, primary total, primary tooth
pacs worlds » places worlds, laws worlds, class worlds
worlds does » world does, words does, worlds die
2000 pacs » 2001 pacs, 2002 pacs, 2003 pacs

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

• If you are trying to use Boolean operators, they must be ALL CAPS: 2000 pacs worlds does ((primary tool) OR (primary animal)) regime.
• Adding a wildcard symbol may retrieve word variants: 2000 pacs worlds does ((primary tool) or (primary animal)) regime*.