Perhaps you should try some spelling variations:
"occupational opportunity" » "occupational opportunities", "exceptional opportunity", "generational opportunity"
"educational opportunity" » "educational opportunities"
"occupational mortality" » "occupational mobility", "occupational contact", "occupational activity"

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: (((("occupational opportunity") OR ("occupational mortality"))) OR ("educational opportunity")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"occupational opportunity\") OR (\"occupational mortality\"))) or (\"educational opportunity\"))".
• Removing quotes may allow a broader search: (((( occupational opportunity ) OR ( occupational mortality ))) or ( educational opportunity )).
• Adding a wildcard symbol may retrieve word variants: (((("occupational opportunity") OR ("occupational mortality"))) or ("educational opportunity"))*.